What's the best EL84 amp?

For me?  Dynaco/Dynakit ST-35

I wish I had efficient enough speakers for that amp. I've heard really good things about it. In the end, I was disappointed in the RM-10 I and II compared to vintage EL84s that I have tried. Same with the Manley Mahis. Just no enough back to front imaging. Everything is so midrange-y forward.

I recently acquired a custom Aric Audio EL84 amp and must say I am mightily impressed. And I have owned an RM-10 II as well. The Aric Audio amp has that special midrange magic of the EL84, but brings bass depth and dynamics to the table.

Looks like it's been 3 years since one of those popped up for sale.

Grommes PHI-26

Just to update in case anyone is interested. I got and had rebuilt a Fisher SA-100 which is the best sounding EL-84 I've heard out of all of the ones I've had. Simply, it has everything all the best ones have, near SET delicacy, but also BASS! I tried a Luxman vintage OTL and that sounds awesome but a little thin.... needs a preamp with tone controls.

The 6L6 amps I liked were old, vintage, RCA and Northern Electric amp, and the crazy expensive Western Electric 124 amps (they run 6L6 or the 350B tube).I have heard a number of custom built amps that use this tube.  The similar sounding KT66 is used in amps made by Synthesis Audio, an Italian company.  I really like their A40 integrated amp (2 output tubes per channel, 40 wpc) and their 100 watter the A100 (4 tubes per channel).

@larryi I have relatively efficient speakers (Altec Model 19's), but feel the large woofers still benefit from moderate to high powered tube amps.  What 6L6 based amps do you recommend, assuming a min. of 40 wpc?

I should try one. Those are two tubes I have not listened to, not counting a Quad amp I borrowed for a day.

dhcod,

I like your description of a good EL84 amp--the sound is lively and "fun" and they can be a bit "rough around the edges."  Have you heard a good 6L6 or KT66 amp?  These tube types have a slightly richer sound and are often a bit less rough sounding than the EL84 tube.  

So the best that I've heard so far is the Scott 222C. Wow. Sounds like my SET but with more power. It's an integrated with Amperex EL84s, a Mullard 5AR4 and Tele 12AX7s, but it sounds great even bypassing my Lamm preamp. A tiny bit rough around the edges so I'll send it out to be restored but super fun amp.

Others listened to: Manley Mahi, Music Reference RM-10 Mk1, Heathkit UA2, an Eico, a Leben (EL34), Scott 208 (5791s).

The Fisher Chassis SA-16, such a surprising little amp from Fisher originally used in a console way back in the 60's.  

David Weinhart, (The AV Experts) an EAR retailer and friend of the distributor, Dan Meinwald, uses the SR purple fuse in his 912 which he has owned for over a decade. I recommend after using the blue in my 864 and purple in my 890, that you should try a purple fuse in your 868L and be surprised at the very significant improvement, especially in opening up the inner soundstage of instruments and voices (separating them) with more body, tighter bass and smoother highs. After just one hour, it was very good and only gets better (I’m not at 200-300 hours as recommended for full benefit, just 45 hours now).  Probably obtain an amperage rating twice as high as a glass fuse.  Dan Meinwald makes maximum recommendations.

Moderator-I am not associated with either the retailer or the distributor, although a customer of both.

Not any longer. I lived in SoCal (Glendale, Sherman Oaks, Burbank, Tujunga, and finally Palm Desert) from 1979 until February of 2016, when I moved up here to Vancouver Washington, just across the state line (the Columbia River) from Portland Oregon.

Ya know, the 868 is available both as just a line stage (868L), and as a full function (line and phono stages) pre-amp. I too would love an EAR 912 (Art Dudley said it was the only pre-amp he had heard which competed with his Shindo), but unless someone dies and leaves my some dough that ain't gonna happen! 

We attended the same show (I attended LA/Irvine shows for decades) and I also said hello to him but I think it was in 2015-6 (I’ve owned the 864 and 890, 324 and Acute since 2006, sold the Acute and prefer the 864 phono stage to the 324 for a Dynavector 20X2 L). The huge difference in quality in use was installing a Synergistic blue fuse in the 864 and a purple fuse in the 890. I use Stillpoint SS Ultra footers under the 864 and SR MigSx under the 890.

I don’t know if after what I have done to modify and tremendously improve the 864 is as good, less good or better than the 912 which I contemplate(d) purchasing. I guess I need to hear a 912 with a SR fuse to determine that (your 868L is a 912 line stage). Do you live in the LA/Orange/Ventura County area?

Exactly @fleschler. Roger and Tim were the only members of a mutual admiration society ;-) .

About ten years ago I entered a room at the hi-fi show held by the airport in Los Angeles, and was surprised to see Tim de Paravicini sitting in a chair, no one around him. I sat down and had a nice conversation with him, during which he told me a lot about tubes. Like Modjeski, he was an expert in the subject, and considered the tube amp designers job to be to maximize the quality of the signal coming out of a tube (or set of them). The loss of both Roger and Tim is a real tragedy for hi-fi music reproduction.

I don’t own an EAR amplifier, but I do own (and love) an 868L pre-amp, best one I’ve ever had.

@bdp24 Well, my best friend has a personally upgraded RM-9 and I have EAR 890s (with an SR purple fuse sitting on SR MiGSx footers) and our systems maintain a very similar in sound character-resolution, tonal balance, dynamics, bass, rhythm (despite the very different speakers VS35 Export vs Legacy Focus, respectively).  Apparently both RM and EAR products have design as their primary features with sales as an adjunct (Paravacini was primarily a pro-audio guy who happened to build a big home audio business).  

@pinthrift We're around to fix the Music Reference amps but will no longer touch them if they have been modified or have had unauthorized parts used in them. The latter would include after market "boutique" fuses.

For the record Roger updated the fuse specs to 250 mA ceramic (not glass) fuses from the original 160 mA spec. We have them here or you can get them from reputable sources online such as Mouser or DigiKey. Roger's preferred fuses were made by the Littelfuse company.

@bdp24 Beat me to it :)

@pinthrift: For Roger’s thoughts, advice, and warnings about "hi-fi" fuses, make sure to read what he posted about that subject on his AudioCircle Forum. In fact, do NOT install any in your RM-10 until you have done so. Roger is not around to repair your amp if you don’t.

Hey again on this topic, directed to owners of the Music Reference RM-10 MKII amplifiers?  Roger Modjeski chose to engrave into the top plate of the amplifier the actual value next to the 2 plastic screw positions "160mA Slow."  In reading the threads above, it appears that some amps came back to Roger due to aftermarket fuses creating damage.  

I've been considering upgrading the fuses in my RM-10, staying, of course, with the "160mA Slow" blow value recommended by Roger.  I would welcome anyone who has had any experience with a fuse upgrade for this amp?  Blowing up aftermarket fuses could be extremely costly, and I certainly don't want to risk damage to the amp.  

Thank you for any feedback, Pin              (bold print for old eyes)

It was Roger’s electrostatic loudspeaker that I thought was the last product he introduced as a "stock" (at least by Modjeski standards ;-) Music Reference model. And I understood it to be available either with or without the direct-drive OTL amps. Perhaps that too is a myth.

I DO know his ESL included dynamic woofers (for 100Hz down). Roger told me he considered the bass of the Quad ESL to be inadequate, that the bass panels had a resonance which could not be eliminated. As I said, he advised me to use a symmetrical 24dB/octave filter when employing a sub (I’m inclined to consider a driver coming in at 100 Hz for use with a planar as a woofer, not a sub, but that’’s just a matter of semantics I suppose) with the Quad, necessary to make the resonance inaudible. As his own ESL included a "sub", and as he told me he considered the Quad’s bass reproduction to be inadequate, and was adamant that the x/o filter be steep, I guess I just came away with the assumption that he used a dynamic woofer with his Quads. I am in fact surprised he didn’t. For Quad owners looking for a woofer, the Rythmik plate amps include a 24dB/octave settings on their crossovers.

Roger stated in his Music Reference AudioCircle postings that of the MR amps returned to him for repair, it was most often as a consequence of botched modifications, usually for nothing more than the replacement of his stock parts with "magic" parts of the same value (including "magic" fuses ;-). When looking for MR amps I therefore always made sure the ones I bought were unmolested, 100% stock. I got my RM-9 from Sheila Berdan, and as Brooks was a MR dealer the amp may have originally been bought from him. Kismet? ;-)

As to the "lightweight" sound of the RM-10: when mated with a typical high-sensitivity loudspeaker, that may actually make for a synergistic pairing. Many of them have bass I would characterize as "woolly" (not a fan of the bass-reflex design).

@clio09 the Stingray came with Yugoslavian EL84s which were blown up quite soon. Russian military ones are close to permanent, i replaced i think just one kit (during 20 years) and two or three of them didn't give enough bias and I replaced them. I have a number of these tubes and may ship some to you. 

@dhcod Well you would have had to jump on the 405 so doubt we passed each other. At the time I lived in Santa Barbara 3 miles from Roger :) I have the only remaining pair of ESLs with the direct drive amps. One of these days I’m going to have to hook them up. Roger figured out a way to increase the dispersion of the treble in the panel to create better imaging. Roger mentioned to me it was something Jim Strickland was onto as well but Acoustat went by the wayside before the work could be finished.

@niodari The Russian military EL-84s (Soviet Era) and Yugo EL-84s were Roger’s preferred tubes for the RM-10. Both are excellent choices. I’m very curious about the Manley EL-84 amps and think a set of Mahis may be in my future.

Marantz 8b.

I didn't read all posts.  I have been using Manley Stingray for almost 20 years. The EL84 tubes i have with this amp are Russian military ones, they are very reliable and sweet sounding. 

His ESL sounded incredible by the way!

I heard those ESLs around that time. We probably passed each other on the 405. I went to see him a couple times to work on my RM-9. He discussed wanting to buy. ARC, which was rumored to be up for sale at that point, because he knew everything that was wrong with their circuits. I called a VC friend but it never got any further than a theoretical conversation.

@bdp24 Sorry if you felt I was churlish. Just trying to set the record straight and it's probably something I picked up from Roger himself after many years of listening to him trying to set people straight about all things audio. He certainly didn't suffer fools gladly.

The ESL direct drive amps designed by Roger were never meant to be a product per se. The first ones were actually designed as a custom project for some Acoustat owners down under who wanted to replace the pitiful step up transformer that was originally designed for the various Acoustat full range ESL models. Roger appreciated Strickland's ESLs and they influenced his ESL designs. Roger was also very familiar with the Acoustat direct drive amp and designed a tube input stage modification for it that a few folks have benefited from. So he designed an all tube direct drive putting 5000V on the panels without that pesky interface for those very lucky Acoustat owners.

When Roger decided to build an ESL of his own, the earliest of which I knew of was around 2003, it wasn't used with a direct drive amp and it wasn't full range, it only went down to 100 Hz (as it was with all his other ESLs) and was biamped. I remember going over to his house to pick up a box for my RM-9 and he invited me in to listen to them with none other than Kavi Alexander who had dropped off his Beveridge ESLs for Roger to fix. It wasn't until he built the direct drive amp for the Acoustat guys that Roger built one for his ESLs (which required less voltage, I think around 3500V).

I would have to say Roger's last "product" was the RM-9 Special Edition. Limited to 20 pieces it is an all point-to-point wired circuit using an additional pair of driver tubes, 6BQ7s at that, and adding another 25 watts of power. Just about everything else was the result of custom orders and small batch efforts (ex. EM7 amp). Even the OTL 1 amp had only 6 pieces produced (on a RM-200 top plate where Roger didn't even bother to hide the RM-200 logo).

Roger's idea of "product" was very different than industry norm. He felt that as the designer he could make changes whenever he wanted without having to document or re-badge the designs. This is why there are 4 versions of the RM-10 MkII sitting out there. He kept most everything in his head but in the final year we pulled enough out of him to hopefully bring forth some posthumous designs that audio enthusiasts can enjoy. So yeah, in more ways than one that ESL direct drive amp was not Roger's final product by a long shot.

Thanks for the corrections, clarification, and additional information @clio09 (in spite of your subtly churlish tone ;-) .

May I ask you to elaborate on your "Not by a long shot" response to my statement that the ESL/OTL was Roger’s final product? I know he had also introduced a number of single-ended amps in his final years. Or was "Not by a long shot" said in relation to something other than whether or not the ESL/OTL was the last product Roger introduced?

My first hi-fi amplifier was the Fisher X-100-A integrated (bought used in 1968), which used the 7189 tube, an EL-84 variant. A nice place to start ;-) . My first guitar amp was a 1966 Fender Deluxe Reverb, also a sweet little amp.

As someone who worked with Roger Modjeski for the last 5 years of his life, and to who (along with a couple other long time friends) he entrusted his business and legacy with upon his passing, I see I need to clear the air here.

A lot of facts about what Roger did and how he did it have gotten twisted over the years, to the point of becoming myths. Roger tried to set the record straight a number of times but finally gave up. I think he eventually came to view the myths as a source of humor, to the point of proliferating them. Roger and I spent his last few months speaking daily at length about many things audio (including the myths vs. reality) and personal. We listened diligently to his interviews with audio luminaries like Julius Futterman and Saul Marantz. I have all his notebooks and designs (at least the ones he documented) that I have been reading and studying so I think I have a pretty good idea of the man and his legacy when it comes to audio.

@bdp24

I got myself an RM-10 for a specific application, one for which the amp is perfect: the Quad ESL. Roger used that loudspeaker and the 16 ohm LS3/5a as his speaker load in the design phase of creating the RM-10, the Quad a notoriously difficult speaker to drive.

The Quad ESL was never used in the design process or as the load for the RM-10 and it’s debatable that his Chartwell LS 3/5a speakers were either. The Quad just happened to be the speaker Roger was using in his system when the amp was designed so after playing it on them just to get a listen to it he felt it was a good amp for the speakers, but a bit lean in the bass.

I have always used subs with my Quads, as did Roger.

Maybe you did but not Roger, although he certainly felt that it would be a benefit to do so, which is what he told me as he sat next to me listening to my RM-10 power my Quads. So next day at his shop we made up some woofers, I grabbed a solid state amp off the shelf, and Roger gave me a Beveridge RM-3 active crossover so I could biamp the Quads in my system and I never looked back.

In the 1980’s (I believe it was) Roger was hired by Harold Beveridge to design and build the tube amps included in the Beveridge ESL.

It was the late 70’s when Roger worked at HBI and this was probably the classic of all the myths. Roger never designed or built those direct drive amps. He did test all of them which is why you will see his name inside them, but design and build - no. Roger did design the Beveridge RM-1 preamp, it’s RM-2 power supply, and the RM-3 active crossover. Roger remembered this period of his career fondly as he got to focus on what he truly loved which was design work. As he often told me, at HBI I designed it, someone else built it, and someone else sold it.

Roger’s final product was not just his own ESL loudspeaker, but one with no input transformers (the cause of a lot of non-linearity).

Not by a long shot.

The Fisher (chassis) SA 16. Find one rebuild it and enjoy.  Supper great under the radar tube amp originally used in a counsel why it’s called a chassis amp.  One of the best little el84 amps I’ve heard ever. 

@pdreher

Let me begin (oh no, here he goes again ;-) by recommending you head over to the AudioCircle site, where you will find a Music Reference section in the Forums. Roger was eventually kicked off it, but before that happened he posted for a number of years, providing his thoughts on a lot of technical issues, including those related to the design of all his amplifier models. Really fascination stuff.

As I previously posted in a thread here on Audiogon, Roger told the story of Tim de Paravicini (one of the few hi-fi amplifier engineers/designers with whom he felt "aligned") telling Roger he could predict the bass response of a power amp by looking at it’s output transformers. It is well known that the more "iron" there is in a transformer, the better will be it’s reproduction of bass frequencies. Conversely, the worse will be the sound of the reproduction of high frequencies. Everything in hi-fi design is a matter of design choices, trade-offs that must be made. Every design choice comes at a cost.

Roger Modjeski was not a "normal" hi-fi company owner. He freely admitted he didn’t enjoy running a business, or even building "product". What he liked was designing, finding solutions to engineering challenges. He stated every amp he offered was an answer to a design challenge, not just another amp. He didn’t design or build an amplifier to have a certain sound, but rather to be stable, linear, and distortion-free. To have no identifiable sound of it’s own. Of course, that is the oldest mantra in hi-fi, but imo he took it more seriously than do most amplifier designers. To hear Roger discussing amplifier design in the flesh, search for the YouTube videos of the talks he gave (three of them) at the annual Burning Amp Festival in San Francisco.

In the RM-10, Roger set out to prove that 35 watts could be created by a pair of EL-84 tubes, twice what anyone else had ever been able to coax out of that tube. Damned if he didn’t do it! And without sacrificing tube life. You can learn how he did it by watching the Burning Amp videos and reading the Music Reference sections in the AudioCircle Forums.

The RM-200 was Roger’s answer to the challenge of designing a tube amp that 1- was optimized for powering low-impedance loads, and 2- produced a hundred watts out of a pair of KT-88 (or 6550) tubes. Again, twice the normal power created by those tubes. I got myself an RM-200 specifically to drive the midrange/tweeter panels of my Magneplanar Tympani T-IVa, a notoriously inefficient planar-magnetic speaker. 100 watts is not nearly enough power for a T-IVa run full range, but the speaker is very easy to bi-amp, something Magnepan urged Tympani owners to consider. Used with a brute amp on the bass panels, the RM-200 is enough for the m/t panels when used in a moderately-sized room.

I got myself an RM-10 for a specific application, one for which the amp is perfect: the Quad ESL. Roger used that loudspeaker and the 16 ohm LS3/5a as his speaker load in the design phase of creating the RM-10, the Quad a notoriously difficult speaker to drive. If an amp can remain stable, linear, and distortion-free when driving the Quad, powering just about any other speaker is a breeze. Not an inefficient, low-impedance speaker, of course (for that he offered the RM-200).

As for the bass characteristics of the RM-10, that was immaterial to me. I have always used subs with my Quads, as did Roger. Removing the low frequencies from the bass panels of the Quad and the amplifier driving them results in a significant improvement in the sound of the combo, PROVIDING one has a sub/woofer of sufficient quality. I have the best: the Rythmik/GR Research OB/Dipole Sub, THE woofer for any and all dipole loudspeakers.

The RM-10 and RM-200 came years after the RM-9, Roger’s first and most "conventional" amplifier. Roger started his hi-fi electronic career the same way Bill Johnson of ARC did: by repairing broken stuff. Johnson owned a repair shop, Roger worked in one while attending college. Roger made a point of investigating and analyzing the design of every amp he repaired, taking note of what caused them to fail. Building a dependable, trouble-free amplifier was a very high priority for Roger. In the RM-9, Roger’s goal was to create the most stable, linear, distortion-free push-pull/ultra-linear tube amp he could. One that provided long tube life, and of course superior sound. In his review of the RM-9 Mk.2, Dick Olsher asked the rhetorical question: "When we have the RM-9, who needs the McIntosh MC-275?" I haven’t owned a lot of amps, but I can tell you the RM-9 is a better amp than the ARC’s I owned in the 1970’s (of course that was a long time ago, and ARC designs have greatly evolved).

In the 1980’s (I believe it was) Roger was hired by Harold Beveridge to design and build the tube amps included in the Beveridge ESL. Roger had previously discovered and become intrigued by the Futterman OTL amplifier, and he worked hard at solving the engineering problems that amp design presented. Roger’s final product was not just his own ESL loudspeaker, but one with no input transformers (the cause of a lot of non-linearity). Already an unheard of idea! But Roger went further, designing and building an OTL amp specifically to drive his hand-built, transformer-free ESL panels.

Think about it: the output tubes of an OTL amp directly driving the ESL panels themselves. Talk about transparency! By the time the ESL/OTL had gone into production, Roger had moved from Santa Barbara up to the Bay Area. I was out in Palm Desert, and was unable to make it up to his new operation to hear his masterpiece before Roger’s illness made that impossible. The biggest regret of my hi-fi life.

Thank you. Very useful info!

I’m thinking now of keeping the RM10 and assembling a ESL57 system with an LP12 and a Marantz 7 Pre. An all mid century looking system!

...oh, footnote.  Those of you running the RM-10 to less efficient speakers...in my Pro DAC, I send below 80 cycles to a sub, lifting the power-draining deep bass duties from the amp.  A lovely solution.  Pin 

Hi dhcod, thanks for the EL84 question.  

As a young man, I first came across the Music Reference electronics in a large, comprehensive publication from "The Tweak Shop" in the mid 1980's, a California retailer for Music Reference.  Having experienced early McIntosh tube gear, I craved ownership of RM but had neither the budget nor confidence in the stability and longevity of tube amplification from that era.  Through a compounded series of good fortune through good friends, I was able to purchase a RM-10 MKII a few years ago.  It replaced my groundbreaking, purchased used NAD M2 Direct Digital Amplifier, a $6K all-in-one approach.

My niche in our hobby is finding the best I can possibly afford, THEN going to work to improve the design.  For example, the NAD M2's cheap case rings horribly, inexcusable for the price and a much-needed fix.  (I'm pleased to note, NAD's new designs have addressed this.)  After doing due diligence around the RM-10, I was NOT about to mess with Roger Modjeski's design.  Interestingly, in switching amps, the humble 35W per side vs the 250W per NAD, the dynamics were greatly improved!!  The perpetual mystery of audio.  

I first experimented with tube sets, which can be had for under $150.  Next, I applied a full complement of Marigo Audio Lab VTS tuning dots, drawing out its deeper truth.  A large "head's-up" to RM owners...do pay attention in cleaning the connector contacts found INSIDE the amplifier as well.  There are O-Ring connectors on the inner wires.  My two previous owner friends were unaware of this requirement and there is goodness to be had!  I experimented with power cords to the amp, finding a sweet spot.  Then!...despite my work under the hood, under both the amp and my Focusrite Clarett Pro DAC, I further isolate with one of these:

IsoAcoustics zaZen Series Isolation Platform 17" W x 15" D: zaZen II (40 lbs Max) (amazon.com)

Now, I don't know exactly where the improvement is being made, but the  improvement is similar to a tangible cartridge upgrade.  IsoAcoustics also makes a larger platform for heavier applications.  

So there you have it.  In my experience, excellent affordable gear CAN be improved upon in cost effective and tangible ways.  Do the homework and enquire from knowledgeable, reasonable people.  Uber power, room speaker integration and carefully integrated affordable gear, can get very close to the crazy stuff, and be absolutely gratifying.  The Music Reference RM-10 MKII found a permanent place in my approaching dotage system.  Ever onwards!

(bold print for old eyes)            More Peace & even order harmonics!  Pin

All true so far. My guess is it's going to be a great amp to have, sitting next to my SET when I am on a non-bass kick. I sounds awesome and is a work of art.

I was hoping to replace the SET but maybe I just need to keep two amps to use depending on the mood...

The RM-10 is magical in the mids, silky in the highs, but bass shy.  I have run mine regularly with a subwoofer.  

@dhcod It’s the amp. I tried to solve the lean base issue with tubes as well. It didn’t work. A subwoofer will though! 

Bent

1+ Manley Mahi Mahi.  Terrifically musical, easy to bias and run great current.  Took them to a shop once to demo their Martin Logans ESLs and they ran the crap out of them.  Salesman was shocked.  They are fun.

It has lovely balls. It's winning me over.

...with huge transformers. I wonder if that's the difference?

@dhcod Yes, sort of. After dealing with the large potted transformers on the RM-9 which accounted for quite a bit of it's weight, Roger wanted a tube amplifier with a small footprint that he could easily carry around. So for the RM-10 he made much smaller transformers and compensated for them with networks in the circuit. The amplifier is extremely flat from 30 Hz to 20k Hz, but things start easing up below 30 Hz, so that might be what you are hearing.

At the time of it's design 35 watts from a pair of EL-84s per channel was double what other designers at that time were getting out of two pairs of the tube. Putting 700 volts on the plates was unheard of, until Roger did it. This is why the amp punches well above it's weight and has a pretty nice set of balls.

@dhcod I occasionally swap in an Elekit 8600R 300B SET amp.  While it does sound nice with the Altec's, the bass is not as well defined compared to the RM9 MK2.  I have Werner Jagusch (MassMutter) crossovers on order... so I'm waiting for those to come in before I decide to try another amp.  I'll likely keep the RM9 MK2, but maybe fiddle with finding a backup.

pdreher, you may want to try a SET amp with those Altecs. You'd be surprised at how much you can get from 9W with very good iron. So far, my new RM-10 is actually a bit bass shy compared to the 300B SET amp I have. I've ordered other EL84 tubes to see if that's why but it's noticeable vs the SET and an old Scott EL84 amp I have. Both are tube rectified with huge transformers. I wonder if that's the difference?

Good question.  Many believe the EL84/6BQ5/7189 to be the best sounding non SET tube.  Power is limited to 15-25wpc in most applications however and that can be a problem for some.

I do have experience with this tube and amplifiers using this tube.   I have a fully restored Eico HF81 which sounds divine driving Spendor 15ohm LS3/5a speakers.

I am intrigued by the Musical Reference RM-10-II and will investigate it.   

I would also look at LEBEN for a new or recent amplifier.  My opinion of LEBEN in general is that their equipment is like a tube amp from the golden era that is restored and brought up to date with modern higher quality components but keeping the classic design.

I would look at the following vintage amplifiers:

Fisher 20a and 30a monoblocks.  Fisher SA100 stereo amplifier.  All 3 are superlative.  Deep bass, liquid midrange, and clear extended treble.

Eico HF14 monoblocks and HF86 stereo amplifier.  The HF14 may be the real prize- as it uses the same amplifier circuit and output transformer as the very well regarded HF81, and EF86.   But with a separate power supply for each amp.  This will improve isolation and deep bass response.   Prices are starting to rise for the HF14, but a cheaper way in may be through the HF12, which is a mono version of the HF81, or an integratged version of the HF14.   A simple rebuild to bypass the preamp stage and you have an HF14 at a lower cost.

@bdp24 How would you compare the sound quality of an RM-9 MKII vs, RM-10 MKII?  I've been enjoying my RM9 MKII for 6 years, but recently replaced Harbeth 40.2 speakers with significantly more efficient Altec Model 19's.  The Altec's sound excellent with the RM9 MKII, but given their high efficiency, I've always wondered if replacing the RM-9 MKII with the RM-10 MKII with provide sonic benefit.  I'm guessing no, but the thought persists.

I think the SIT-3 needs a very particular type of speaker to work well, that being high efficiency but low impedance.  My quintessence are low to mid 90db efficient with a 4 ohm nominal load.  I also have a pass x 150.8 but it never leaves class A with my speakers and the SIT-3 is ever so slightly sweeter.  I'll list the 150.8 for sale soon....

I couldn’t agree more @dhcod. Brooks was also an automobile enthusiast, and had a nice little stable of ’em. Riding with him in his souped up Mercedes Benz to Vegas for the CES was an experience I’ll never forget!

In his younger days (high school) Brooks played drums, and when the band I assembled to play at his 50th birthday party (at the behest of his wife Sheila), he got up on my set and played "Wipe Out" with the band. Happiest I ever saw him! I feel like part of me died with him.

Interesting! I had a SIT-3 with my current setup and it just didn’t surpass the Sun Audio 300B and its 9 WPC. I really wanted it to work. Maybe I gave up too soon?

I miss Brooks more than anyone I’ve ever know in audio. What a gentle-man. I’ll never forget the day he gave me the key to the museum to have a look around.

Nor will I @car123. Or my RM-9 and RM-200, for that matter ;-) . Brooks Berdan had a fairly wealthy clientele, and he was more than happy to sell them VTL and Jadis amps (cha-ching ;-). But he recommended the Music Reference amps to his clients who wanted not just great sound, but great value as well.

Music Reference owners tend to keep their amps a long time; buyers of many other brands seem to always be looking for something better, constantly changing in hopes of finding whatever it is they are looking for. Roger Modjeski was a musician, and his priorities in reproduced sound closely aligned with mine. As did his taste in music.

Roger felt that the electrostatic loudspeaker design was the over-all best reproducer of recorded music. He was a longtime QUAD ESL owner, and used that speaker as his load in the development of the RM-10. His last product was his own ESL, with his own woofer design for 100Hz and below. He advised me to use symmetrical 24dB/octave filters with my QUAD ESL/sub setup.