Bought an Audio Research Amp

I feel like i should preface this with a basic rundown of my system up til now:



Amp: Legacy High Current Amplifier (rebadged CODA Stage 3.2)

Dac: SMSL M400

Transports: Auralic Aries Femto/Sony DVP-S7000

Speakers: LSA-10 Signature

Subwoofer: Recapped Velodyne Servo-1200


Anyhow, as the story goes, I recently acquired an old Yamaha RX-770 on the cheap, figured maybe I’d gift it to a friend. When I inserted it into my system to test it, I was shocked by how good it sounded. It sounded really close to my separates. Worse yet, the Yamaha actually made much better bass through my speakers (sub was off). It was louder, faster, and better controlled sounding. This was extremely distressing. 

I thought maybe this was due to the age of my CODA, but the yamaha is actually about ten years older, so that didn’t make sense. The best I could come up with was just a poor match for my preamp. I can’t recall the figures off the top of my head, but i did some math when I bought the amp to ascertain if matching them was appropriate, in terms of both input sensitivity and impedance, and recall that both were  toward the bare minimum.

Having read numerous times that the increase in synergy is substantial between ARC components, I started casually shopping online for an ARC amp. I briefly entertained a VT100 MKIII which seemed a good deal, but the price of retubing it currently is around $1000, and i just don’t think right now is the time for me to jump into tube amplification with the soaring prices of tubes.

A 300.2 caught my eye, but I couldn’t find any information online that convinced me that a Tripath class-d design of ten years ago would better a solid class a/b design, and I can’t really afford to buy an amp just to find out.

Fortunately, I came across a craigslist ad a week ago for a D400 located only an hour away from me, at a price that was a fair bit lower than similar models had sold for recently (as per Hifishark). Awesome. 

I spoke with the gentleman who had listed the amp, and it turned out that he was the proprietor of a stereo service center, and was selling it for a longtime customer who had been using it, along with 2 D200’s and a D300, to power an eloborate horn speaker setup, but who had, due to the onset of Alzheimer’s, become unable to manage the complexity of his own system. This is, I have to say, extremely tragic. The store’s owner told me the amp was in great shape, had been well cared for, and due to being used in a high efficiency setup, had never been run hard.

Needless to say I was extremely excited at the prospect of owning a D400. Wasn’t able to uncover much in the way of reviews, but I was able to find that it shared circuit-design lineage with the extremely well-regarded d240 MKII, as well as reports from other users who’d paired it with an LS25 and reported extremely positive results.

So I made an appointment to bring my preamp down and auidition the amp. When I arrived, the store owner was extremely friendly, more than happy to take the time to talk audio with me,  show me his personal system (Threshold/Altec VoTT), and all the amazing gear he had on hand, even though I showed up shortly before his usual closing time. 

And the Amp? I really wasn’t prepared for how colossally huge it was… it really is a monolith, just beastly.As far as the sound goes, well, let’s just say that by the time I’d been listening to it for 5m, I already knew i was going to buy it!

Once i got it home (nearly destroyed my back getting it out of the trunk), and into my system, it sounded even better! Compared to the CODA, highs were more sharply focused, I gained more of a sense of instruments existing in specific “space”, and the bass/mid bass had tightened up considerably while also increasing considerably in terms of volume and impact. Overall, I’d say the sound is   less on the warm side than the CODA, which I think is better for my speakers  which have a pretty laid back character.

I will, say that the amp runs pretty hot, even at Idle. I don’t know if it’s biased pretty hard into class a, or what. Also, it does does take 2-3 hours of warm up before it sounds at it’s best. I’ve taken to power it up the night before if I’m intending to do a lot of listening the following day.

Really, I couldn’t be more ecstatic; I really feel like I took a big step toward being  “there” with my system. Of course that just leads me to thinking about what I need to start agonizing over upgrading next, ha ha!

Big shout out to Kevin at The Stereo Workshop in Eugene, OR for being such a gracious host and giving me such a fair shake.


Great story. ARC makes quality gear and I am not surprised by how much your sound has improved. Happy Listening!

@rfnoise -Congratulations! Few things in this hobby compare to finding a piece of audio equipment that exceed expectations. I moved up the ARC foodchain, starting with a LS3B pre-amp. Once you get hooked on the ARC sound (not overly warm/romantic or precise/etched) listening to music is always a pleasure.

Happy listening!



I began with a used entry level preamp 40 years ago and upgraded and added more ARC as I could afford it. Now at long last I have all ARC Reference equipment. Well worth the slow journey. Outstanding company, equipment and sound.

If you like it, then good for you.  ARC shouldn't be going away any time soon, so you should have good manufacturer support.  

Hey, thanks for the kind words, guys. I really am loving it right now with my system.


Some of your comments RE the synergy between ARC components were influential in convincing me to pull the trigger, even though they weren’t directed my way specifically, so thanks.

I’m thinking maybe trying some different speakers might be my next move. If anyone has any thoughts on what pairs well with the gear I have in a small room mid/nearfield setup I’d love to hear them. 


A good story with a happy ending, gotta love that!
Cheers to you B, enjoy your system!

I've been using a D400 Mk II for more than 25 years (currently in a secondary system, along with an ARC LS3). Will probably be using it until I die.

@rfnoise -

"I’m thinking maybe trying some different speakers might be my next move. If anyone has any thoughts on what pairs well with the gear I have in a small room mid/nearfield setup I’d love to hear them. "

What are your musical tastes and budget?



I have used focal speakers with AR tube Amp/preamp setup; i am comfortable listening with beryllium tweeters. my taste  mostly jazz,instrumental,Vocal. 

Depending on your Budget and musical taste, many options are available.



My taste in music has become pretty diverse. When evaluating a new piece of equipment I tend to play Dire Straits’ “Communique”, Natalie Merchant’s “Tigerlily”, and Fleetwood Mac’s “Rumor’s”, but TBH the music I spend the most time with tends to be electronic. Daft Punk, Deadmau5, Purple Disco Machine, etc.

A little while back I got bored and hooked up a pair of Onix Rocket stand-mounts that had been out of rotation since before I went to my current separates, and initially thought I preferred them to my LSA’s (which are just SO laid back) but after some A/B’ing and more careful consideration what I realized was that what I preferred about the Onix’s was their presentation of higher frequencies, which were a little bit hotter/more forward (not sure if this is a function of their having metal-dome tweeters vs the LSA soft-dome). The mids were somewhat drier and slightly recessed compared to the LSA’s, which I preferred more overall.

On the other hand, I have a pair of Klipsch RF-5’s that were so forward and shouty that the vocals on Daft Punk’s “One More Time” fairly well ran me out of the room in less than a minute.

Some reading has led me to think maybe Thiel might be worth trying out, either the PCS, or MCS1.

Really I’m mostly looking for “food for thought” as to what to be keeping my eye out for as my bank account recovers from this latest upgrade. I’d imagine $2500 would probably be the upper limit on what I’d be willing to spend on a pair of pre-owned speakers.

Glad you love it.  It is hard to beat an ARC product for the most part (no one is perfect).


If your dealer carries Magnepan, have him bring a pair out and see what you think THEN! (In YOUR ROOM, of course.)

You may be pleasantly surprised...



I guess I probably should have mentioned my room… it’s tiny. 14’x12’. My speakers are about 6’ apart, 18” off the rear wall, and my listening position is about 5’ from the speakers. I’m guessing magneplanars need more room to breathe than I have on offer.

A classic combo for really musical, detailed and great soundstage is Sonus Faber.  Olympica ? I think they are about right. But listen to them.. any decent pair. Their sound is very natural and musical… I am on my third pair after abandoning planar after 30 years. For me all genera of music improved and they do not overly emphasize the venue over the music. So, they are all about the music… pretty also.

I don't mean to do anything to dispel your enthusiasm but your solid state ARC brings up an interesting aspect of vintage amps. ARC can not and will not service the vast majority of their solid state amps due to parts availability and the circuit boards previously utilized. They can service any tube amp ever made by them. Although there are no absolutes, tube amps are fundamentally serviceable regardless of age whereas many older solid state designs are not. Time and time again some very opinionated individual on this Board will dismiss tube amps as being expensive to maintain and glorified tone controls and then those same people ask where they can have their twenty year old solid state amp serviced because the manufacturer is out of business and they can't find a tech who can repair it. Total thread drift so apologies extended. 

@rfnoise  You are correct.  A small room is an issue with Magneplaner products.  Possibly the smaller ones might be worth a try(?).

Whatever, try it out IN YOUR ROOM and be sure YOU are happy.  There are no "perfect" choices for reproducing music for everyone no matter what anyone thinks.  As a dealer, you soon learn that fact!


@rfnoise -At 200W a channel, you have A LOT of choices. Given your tastes in music I would agree with the poster who said Sonus Faber. I'd also add Totem and the Spendor A or D series. Each speaker has terrific PRaT which is something your ARC combo excels at.

Let us know what you decide upon. It's always fun participating in these threads.

PS-Ignore people telling you that if your equipment breaks, you will have difficulty getting it repaired. There are many options for ARC repair services, IF you need them.

Happy listening!



I’m finding that I tend to prefer a more cool/neutral sound; whatt I’ve read about the Sonus Faber sound tends to use words like “warm” “dark”and “lush”.  Has that been your experience? 


Well that’s disconcerting… it was my understanding that ARC stands behind their heritage products regardless of age. I mentioned that the person who brokered the sale was a tech; he said that when his customer brought it in he opened it up for a bench test, and everything checked out within spec, so hopefully I won’t be ending up with a boat anchor anytime soon. I did ask him if I should be worried about the age of the electrolytics in the amp, and he told me that the “full recap craze” (his words) was a fairly recent development, and that he didn’t believe in replacing something unless it was failing/out of spec. 

It’s interesting that there isn’t a solid state amp in their current lineup. Correct me if I’m wrong, but as far as I was able to ascertain, their last solid state power amps were the DS series, which was over ten years ago.

I have an arc pre I love. I don’t think I’m getting enough transparency of instrumentation from my Pass Labs 25 watts per channel. Would the D400MKll be the answer? It’s easily available at good prices. I have always read as well arc works best with arc and I can't afford the new tube models and worry about used tube units. Would any other Arc solid states be another option?

Me too fell in the audio research trap 3 years ago,  there's no coming back..

After some mods I now have 6n1p on input and 6n6p out in my ls25 mk1 ..

Some day I might have the means to get my self the ear 912 pre , and that may be the end but for now I would not change s thing 

Cheers to a great pre 😁


As a real rookie in this stuff, I don’t really feel qualified to offer advice. At the risk of making an absolute fool of myself, I’ll conjecture that it’s a vague possibility that your Pass Labs may share some distant design lineage with my CODA, as it was built by ex-Threshold alumni. As I stated above, the gains I’ve made by moving to the D400 have been phenomenal. As far as my research has been able to ascertain, in terms of solid state, the D240, 100.2, and D400 are the amps to look at from ARC. I went with the D400 BC even though it’s probably overkill for my current speakers, I find a certain security in having an amp that could handle any speaker I might throw at it down the line.



who did the mods on your pre? Mine is the MKii, with 2 6h30’s, so no tube rolling for me.

I can confirm that ARC cannot repair many of their older SS amps. Dave Gordon told me that himself on the phone. They simply dont carry the parts anymore. Im not talking about stuff made in the last decade but good luck with stuff that was made from say 2000-2010. Your SOL.



On Sonus Faber… the older… say more than 10 - 15 years tend to be warm.

Today’s Sonus Faber, I am uncomfortable using the word dark. They are very natural and organic. But I would not call their sound cool, lean, or highlighting details. I know folks that really like very detailed speaker like Magico… SF is not them… at all.

Hopefully this is helpful.


Any idea which parts are considered unobtanium, and how prone they are to failure? Or any sort of preventative maintenance that could extend the life of my amp?


Thanks, that is indeed informative. Some recent reading indicated that the Concertino is well suited to a smaller room. In any case, it looks like my option is try a bunch of speakers til I find what I’m looking for, which means judicious spending on the pre-owned market, so I don’t get killed on depreciation in the event of a necessary resale. Guess I’ll have my work cut out for me.

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Yes… excellent. That is correct, listen to a bunch of speakers. For me, I went listening to lots of different speakers… then one grabbed me…. emotionally. This was my first set of high end speakers… I was listening to them… they brought tears to my eyes… I bought them. They had AMT (Air Motion Transducers) for the treble and midrange. They got that right..


Your speakers need to connect with you emotionally. It is good to be an analytical… for a while when auditioning speakers. But after you get that unnecessary part out of the way… stop listening to the speakers and listen to the music… when the music becomes compelling… you establish an emotional connection… buy those.


I did the mod my self , needed to change the voltage regulators for the heaters to higher ampere .

as for rolling 6h30 tubes, you could try 6n6p . It's a drop in replacement but with lower current draw .

@rfnoise I have been in love with ARC for abut 4.5 years now.  I took a long journey from an LS3B with the Classic 120 mono blocks and a PH5 phono stage to get to the previous generation of their REF lineup.  I tried out several different line stages and phono stages along the way, but my amp experience was limited to the GSi75 integrated, REF 150 and now the REF75SE.  I had one quick opportunity to hear a D200 that I had purchased for a friend in person and had set up before shipping.  It was a very strong amp and definitely was superior to my backup amp, a B&K REF 200.2 S2.  When the time is right, I would encourage you to try one of their tube amps.  All 4 I have auditioned sounded amazing.  I still have the Classic 120s which I have compared to all the others and still put up a good fight against them all.  I was just ready to move on from that look and the space they took.  I always loved the silver REF look and am quite happy and fortunate to have that lineup now.  FYI, this is straight off the ARC website regarding their limited service. You can find it in their FAQs, models no longer serviceable.

The Audio Research products listed below are NOT serviceable because parts are no longer available.
• Some D-Series amplifiers
o D52/B
o D60
o D100/A/B
o D110/B
o D111
o D120
o D130
o D240
o D350/B
o D400
• HD220
• SD135
• CD2
o SP4
o SP5
o SP7
o 150.2
o 300.2
o 150M

Had a ARCD400MkII for 17yrs.In 2008, I believe, I was thinking about having it recapped and ARC told me back then that they could not get the big PS caps any more.I ended up selling it and bought a Ref110 and I was really surprised that everything sounded better now.What really surprised me the most was how much better the bass response was.Maybe the D440MkII really did need to be recapped was my thinking.

I had the same experiences going from nonARC solid state to ARC tubes.  Don't get caught up in the power ratings either.  When I got the Classic 120 mono blocks I also had a Parasound HCA 2200ii.  I fought hard to stay solid state and picked up a 2nd HCA 2200ii.  If I recall correctly, when bridged those put out 750 watts and compared to my ARC 110 watts the Classic 120s were more dynamic and had about the same amount of volume/output.  The only limitation I experienced was the GSi75 integrated.  I believe it is due to weaker power transformers compared to my REF 75SE.  I have Wilson Sophias in a large room and the bass would drop out/distort at very high volumes with the GSi75.  It never happens with the REF75.  To think I used to have 750 wpc and now I have 75 and the sound is vastly superior in all aspects. 


A wonderful story and thank you for sharing your journey to your exciting sounding system!  


I went to the ARC website and found the same list you posted. Thanks for that. I noticed that neither the d200 nor the d300 are on that list, which is curious, as they are the lower powered contemporaries of my d400. Also interesting is that I found a n authorized service center (High End Audio Repair, in Brooklyn) that lists the d400 as one of the amps that they service/upgrade.

I’m not entirely opposed to the idea of a tube amp; as I stated in my OP, I had my eye on a VT100 mkiii that was on USAM. It was only $1800, which seemed a steal. I just couldn’t get my head around spending $1000 to re-tube it. Hopefully tube prices come down sooner than later.

oh btw… jealous of your Wilsons. In my speaker musings, I’ve toyed with the idea of trying a pair of Tiny Tots on stands.


thats just bizarre! I guess I just assumed that the unobtainium parts would be FETs or something, but capacitors?!

I’m assuming that the caps you’re referring to are the 67000uF 75v ( marked c41, c42, c43, c44 on the schematic). 
I don’t pretend to be any kind of tech, but caps that meet that spec seem to be available.

Here’s one from Cornell Dubilier that’s rated up to 100v

Is there any reason it wouldn’t work in this application?


I had a reluctance to tube amps for a very long time. The idea of retubing. But a few years ago I went ahead. I immediately realized my mistake. It was false economy to me. My system took on a realism and natural musicality (ARC) I never imagined possible (although I had briefly experienced it here and there). But living with it. I will never go back regardless of retuning cost. Realistically when I was working… retubing would be necessary less than once every 5 years. You only live once. I personally wish I had done it sooner.

Thats right rfnoise they were the 67000uf ps caps.As i started thinking about it ARC might have told me that what they found as replacement would not fit into the amp and that they were trying to figure out a way to retro fit these into the amp.I don't know the dimensions of those Cornell Dublier caps you mentioned if they would have been the same dimensions.


Everything I do in this hobby I have to do on a pretty tight budget. My friends all think I’ve lost my mind when they hear how much I’ve invested in my meager system. Having said that, you’re kind of making me wish I’d taken a chance on that VT100…


You know, as I was turning this capacitor quandary over in my head, it did occur to me that perhaps it was the specific dimensions that was the issue. I did a little more digging last night (when I should have been sleeping) and came up with a spec sheet for Cornell Dublier capacitors wherein it lists a number of capacitors that meet the required spec in a variety of dimensions, in regards to both case size as well as terminal spacing.

Unfortunately I only have the ARC part number for the stock caps in my unit, which doesn’t get me anywhere in terms of determining their dimensions.

Losing sleep whilst obsessing over finding a replacement for a capacitor that for all I know is functioning fine. Whoo this hobby is a blast lol.


Yes, I’ve had that crazy moniker on audio for nearly my whole adult life. Even when my system was very modest… but was not modest compared to my meager income.


Thanks for sharing!  I went through a similar journey 5-6 years ago when I finally bought my first ARC pieces, an LS7 tube line-stage and a D240 MKII solid-state amp.  About 4 months later, I added a PH3 tube phono pre-amp, and about two years ago, a second D240 MKII so I could run the amps in mono-bridged configuration.  Speakers were initially Thiel CS3.5’s; this past March, I moved to KEF Blade Two’s (FANTASTIC speakers!!!).  

I really identify with you in terms of valuing system synergy; for me, it’s the most important aspect of a system.  When I had the Thiels, a fellow audiophile told me to consider vintage ARC gear because I could get solid-state amplification and pair it with tubes in the pre-amps for warmth.  He said ARC was one of the best to have ever done this and the sound was absolutely addictive.  I’m glad I listened to him, because the combination of solid-state & tubes, along with that all-ARC synergy, has been incredible!  

Also, as others have said, a very good and reputable electronics repair shop can service our equipment, no problem.  ARC can only service a piece as long as they have the exact part availability; as you’ve pointed out, their are many equivalent parts substitutes or even upgrades that can be used.  The circuits ARC uses are well documented and straightforward; there’ll always be shops that can repair/rebuild ARC gear.

Every once in a while, I’ll get the urge to try something new, but my sensibility comes ‘round…how much better do I need?  Sure, it’s decidedly vintage gear, but it’s ARC & still sound pretty freakin’ phenomenal.  So, I sit down and just enjoy!

Good Luck and Happy Listening!