Benchmark LA4 vs Linear Audio Tube microZOTL Preamplifier (Level 2)


I have enjoyed my LA4 preamp, but I want to see if a quality tube preamp would be more to my liking. I have ordered a LTA MicroZOTL Level 2 and it should be here in a few weeks.

My current set up:

Acoustat 1+1 with a SPL Crossover and dual Rhythmik F12SE subs

Innuos Pulse paired with an Innuos Phoenix USB

Bricasti M1S2 DAC

Marantz 8003 SACD (rarely used)

Technics SL1500 turntable with AT VM540ML cart upgraded with a RigB body

Pass Labs XA 25 power amp

Upgraded, but not excessive, cable

I have a month to compare the two preamplifiers and decide if I should make the move to the dark side (tubes). Everything I have read suggests the MicroZOTL L2 should improve stage presence, separation, and depth without significant detail loss. I do 95% of my listening through Qobuz and Sense with the rest from vinyl. The SACD player is only used for the occasional SACD not offered as HD through Qobuz.

Prior to settling on the LTA I listened to a used Electrocompaniet EC 4.8 Mk2 (had not settled on trying tubes yet.) (poor detail when compared with LA4 and narrower soundstage).   I also wanted to try a Pass Labs XP 22, but could not find a used one to try at home (also prior to the tube exploration).  I auditioned a used ARC 5SE (decent soundstage, but suppressed high end and the bass was underwhelming). 

I am looking for any guidance or suggestions the Agon community might have for me.

Thanks in advance!

Ralph

thriftyaudio

@thriftyaudio For all of my 2-channel listening I use the HPA4 (same as the LA4) and the Holo Audio Serene. The Serene is almost a copy of the HPA4, just a tad warmer. The Serene also sounds nice with Class A amps, such as my CODA #16. Though I keep thinking of trading it for a LA4.

Another preamp that I owned and is always regarded as sounding like a tube preamp is the solid-state CODA 07x (the most recent model). As with many tube setups I found it too noisy in relation to my LA4 (owned before the HPA4).

 

Have you considered using a tube DAC with the LA4? That way you can have the best of both worlds, except for your turntable.

I also have SACD's and use the GEERFab D.BOB to play the DSD stream on my DACs which are better decoders than the OPPO player. Your Briscati DAC should be great with your SACDs. I feel the disk playback seems a bit better than streaming. A shorter path in many ways.

GeerFab Audio D.BOB Digital BreakOut Box (OPEN) – Upscale Audio

@thriftyaudio I used to run XP22 with XA-30.8 then upgraded to X260.8. Big difference across the board. Had Audio Research Ref6 for few weeks as well. Bass was phenomenal. I ultimately preferred the XP22. My DAC is Bricasti M3.

Before you splurge on a new preamp, I would encourage you to try the Bricasti M1S2 preamp section. One other point I would like to make is that the Bricasti DACs sound their best via their XLR outs. It’s very possible that you would get much better results if you upgraded your amp, instead of preamp. Just a thought…

But if you want to go ahead with a preamp upgrade, I would highly recommend XP22. Just run your DAC using XLR cables into preamp. 

FWIW, I replaced a LA4 with a Pass XP-12 and was very happy with the results. I liked the LA4, but it is not as musical as the Pass. 

I’m very happy with my LTA MicroZotl level 2 preamp. I’m using it with a Coda No 8 amplifier.

I bought my LTA lightly used from a guy that moved to a high dollar integrated amp. He had upgraded the tubes to NOS Telefunken ECC801S. I experimented with several other tubes including the ones that he said came with the preamp. I did not like the tubes that shipped with the preamp. I’ve tried NOS Siemans ECC801S which are very nice and less expensive. Brimar Yellow T are warmer sounding and should be available from Tube Depot. In my system, I prefer the Telefunken, but would be happy with the Siemans.

@thriftyaudio - I own the LTA Microzotl preamp level 2. I think you are going to love it. When I first plugged it in, I was shocked what an improvement it delivered compared to my older tube preamp.

Let us know what you think once it arrives! 

@yyzsantabarbara I was hoping you would contribute.  We seem to have similar tastes in audio.  I am hesitant to try a different DAC since I just purchased the Bricasti M1S2 a few months ago.  I compared it directly to a Chord Dave with M Scaler and a Mola Mola Tambaqui (both in my system) and the Bricasti was the clear winner.  Even used it was a bit expensive so I want to hold onto it and enjoy the music.  I like the various filter options it provides to match with recording productions.

@audphile1 thanks for the recommendation.  I have tried the M1S2 without a preamp in line, but the sound became muddled at higher volume.  The LA4 does a better job with the M1S2 than the DAC does by itself.  I am holding out hope that Pass Labs will release a dual monoblock version of the XA25.  I will definitely upgrade the power amp for them!

@zlone thanks for sharing your experience.  I really wish I had found a used XP22 to try in my system.  Maybe I will find one in the next few weeks to compare with the LTA and Benchmark.  The added benefit of a Pass Labs preamp would be the ability to turn the XA 25 on/off with the remote.

@sls883 ​​@bluethinker I have heard nothing but praise for the MicroZOTL Line 2 form several sources.  I have a new one on its way with three sets of tubes (standard plus two different upgrades tubes).  I will not be purchasing additional tubes for this comparison, but I will try all three sets of the supplied tubes.  It should be fun!  

Maybe I will keep the LA4 and switch back and forth.

@thriftyaudio I think you'll like it.  I had two different conrad-johnson preamps before the LTA and I prefer the LTA.

I'd be curious to hear which tube types you try and which ones you like. 

@thriftyaudio - Out of curiousity, what are the alternate tubes you’ll roll with the LTA preamp? I’d love to hear your impressions as I’ve only heard the stock NOS tubes it shipped with.

@bluethinker ​​@sls883 The three tube types are "stock tubes" plus

  • Free Premium Tube Upgrade: Receive a FREE Gold Lion + Ray Reserve 6SN7 tube upgrade with your MicroZOTL Preamplifier purchase

  • as part of the 2024 holiday deals.

@sls883 it will be interesting to get your thoughts on the tubes.

The 12AT7 that came factory in mine were branded Trigon.  From what I was able to learn, they are probably a rebranded something.  They aren't great. 

I have Sylvania bad boy 12sn7gt and RCA 12sn7gt. I don't recall which pair is installed. 

"Maybe I will keep the LA4 and switch back and forth."

Great choice. Get another preamp for variety. If your power amp has a front facing switch to toggle between RCA and XLR inputs, then you can even have 2 preamps hooked up at the same time. You need to see if your Bricasti is good with having the RCA and XLR outputs connected at the same time to 2 different preamps. In my office, I have my Yggi+ OG DAC connected to 2 preamps and a tube headphone amp at the same time.

BTW - My Schitt Yggi+ OG was compared this weekend to the Dave and the Tambaqui at a pretty cool headphone event. I was not there but I got feedback that both DACs were slightly favored over the OG.

"The LA4 does a better job with the M1S2 than the DAC does by itself."

I found that all DACs I had in my system were better served by the volume on the LA4. The only one that came close was the Lumin X1 that has a special Leedh volume control. Even that had a slight gremlin at the lowest volume levels.

As A said in a previous post. I own 2 LA-4 preamps, Love them, my system is all balanced. Rock and Roll, great electronics (in my opinion, ex: Pass X250.8, Bricasti M1SE) Nice feature, adjustable gain, and I run my 2 SVS Sb4000 subs via a split balanced cable run out of the rear mono stage of the LA-4  Just my $02. Robert TN

The MicroZOTL Level 2 arrived last week and I have spent the better part of three days doing critical listening comparing it with the LA-4.  Right out of the box the MicroZOTL (MZ) was a bit disappointing.  The music seemed a bit more muddied (I know, what a wonderful audio descriptive word).  I let the MZ run for a few hours with me out of the room and when I returned the music was cheerful and enjoyable.  

That is when I started the critical listening.  As a rule the MZ was providing a wider soundstage with slightly improved instrument separation.  One thing that definitely improved in these early comparisons is the soundstage and instrument height.  The LA-4 provided an unnatural separation in height with some instruments/vocalists elevated above the soundstage plain.  This is welcome on some music (Pink Floyd's Dark Side of the Moon), but not with quartets or Santana.  The MZ does a great job when the sound should be elevated (some drum kits).  I like the improved instrument placement of the MZ.

After I decided I liked the MZ better than the LA-4 with Qobuz (through Innuos Sense) I started the test again with vinyl, then CD.  It was clear right away that the MZ was right for my system.

Then I started the test over with Qobuz and utilized the Bricasti M1S2 filter options.  My preferred filter was the Minimum 2 (M2) with the LA-4, although I would use the M1 and the Linear 1 (L1).  During my DAC comparison I found the L1 filter most resembled the Chord Dave DAC (extreme detail, almost clinical), and the M2 resembled the Mola Mola Tambaqui (most musical).  With the MZ the M2 is extremely musical and pleasant, but maybe just a touch less detailed than I want.  The L1 and M1 settings both work well with the MZ.  I have not decided which I prefer.

The upgraded tubes from Linear Tube Audio will arrive later (on back order) and I am looking forward to improvements they may bring. 

I was initially planning to keep the LA-4 and the MZ while utilizing a Transparent Selector from Pine Tree Audio and enjoy both pre-amps.  Plans have changed.  While the LA-4 is an outstanding line amp, I no longer need it and will be selling it soon.  The Linear Tube Audio MicroZOTL Level 2 pre-amp will be my long-term solution now that I have stepped into the dark side of tube audio.

@robshaw I was concerned about the lack of Balanced output from the MicroZOTL Level 2 but my cable runs are quite short and the LTA team maintains the RCA link is equal to the XLR (there is a balanced input available that I utilize for the Bricasti DAC input).  Additionally Pass Labs designed the XA-25 without balanced XLR inputs.  I saw that Nelson Pass felt the XLR was not needed for the amp.  I run a XA-25.  

I did run the Bricasti into the MicroZOTL with RCA and XLR and could not tell the difference.  I stayed with the XLR since I did not have another quality RCA pair to keep in  place.  Why spend $ when I don't have too.

All things being equal, my gut says the XLR option should be choice.  However, the RCA option from the MicroZOTL to the SPL Crossover, and from the SPL Crossover to the Pass Labs XA-25 is working great.  I am not going to sweat it.

However, if Pass Labs releases a mono-block version of the XA-25 with XLR input, then I may need to reevaluate my decisions.

I let the MZ run for a few hours with me out of the room and when I returned the music was cheerful and enjoyable.  That is when I started the critical listening.

That’s not nearly enough time for the preamp to burn in unless LTA did considerable burn in before it was sent.  I’d give it at least 100 - 150 hours before making any firm conclusions as it’s likely to sound even better with more hours, but that you still preferred it to the Benchmark after so little playing time is very encouraging (but not all that surprising IMO).  Hope the better tubes bring you even more goodness.  Enjoy!

@soix Thank you for the note.  LTA does some burn in prior to shipping, but also recommends 50 to 75 hours of additional time.  They also have a 30 day at home trial period, with the caveat of keeping the unit for a minimum of 14 days to insure the proper burn in is achieved (my guess).

I have just over fifty hours with the MZ so far.  If there is improvement over the current results, then "Yippee!"  

@thriftyaudio I will be interested in your thoughts on the upgraded tubes.  What tubes are in it now?

I've tried a number of 12AT7 tubes and there are big differences in sound quality between the different tubes. 

@thriftyaudio - I’m happy you are enjoying the LTA preamp. I really enjoy mine. The company is always a pleasure to interact with when I have questions, which is a nice bonus. 
 

Let us know how the preamp continues to burn-in and how the new tubes sound. I have not done any tube rolling myself, so I’m eager to hear how different tubes sound in the LTA preamp. 

to Thirftyaudio: I am very pleased to hear your so happy with the new tube pre amp. Let me know if you would be so kind, as to further improvements, etc. in sound as it burns in. I have never gone down the tube route. (enough rabbit holes exist)  Was always curious about the tube route though.

Just curious about your dual sub hook up to the MZ. Mine is currently split through a mono balanced choice of the LA-4. Not familiar with the rear layout of the MZ. Thanks, Robert

@robshaw Hi Robert.  My Acoustats are inefficient speakers (83 db) and do not generate exceptional bass.  When I first purchased the speakers I added a Vandersteen 2W subwoofer that supplemented the bass and that was a good solution for many years.  A few years ago I wondered how the Acoustats would do if they did not receive any (or essentially a minimal amount) of the bass signal. 

I replaced the Vandersteen with the dual Rythmiks and inserted an active Crossover which limits the signal to the Accoustats (currently at 70 Hz) and the Rythmiks (same 70 Hz).  This helped the main speakers substantially.  The folks at Pass Labs suggested this changed the Accoustats efficientcy from an 83 db to 89 db which allows the XA-25 to effectively drive these power thirsty speakers.

The crossover I utilize is an excellent unit from Germany.  The SPL Crossover allows me to adjust the crossover on the fly, adjust the signal slope, and many other fun tidbits.  Another one I considered was the JL CR-1.  I believe I would have been happy with either (similar concept with a few different options).  The SPL I purchased was a demo unit and I got a great price.  

Sorry I can't help with the LA-4 solution.  An active crossover may be your best option.  There are less expensive active crossovers available, and a few significantly more expensive.  My research suggested the JL or the SPL units would be ideal for my system.  An active crossover might help relieve some of the bass demand from your speakers resulting in a clearer mid-range.

Best of Luck.

Ralph

Thanks so much Ralph. I'm glad you've met with such success in this never ending journey. As I grow older and have many hobbies (time requirements) status quo in the audio arena is not so bad. However, when I hear your system improvements it makes me pause and consider alternatives, thank you, I think!  Robert  Good luck, I'm a little jealous. Robert

 

Thanks so much Ralph. I'm glad you've met with such success in this never ending journey. As I grow older and have many hobbies (time requirements) status quo in the audio arena is not so bad. However, when I hear your system improvements it makes me pause and consider alternatives, thank you, I think!  Robert  Good luck, I'm a little jealous. Robert

 

@robshaw I truly understand.  While I am retired, I am active in two groups (one Board), plus creative writing, woodworking, and honey-doos.  It keeps me busy.

The addition of the SPL Crossover is perhaps the single biggest improvement for my system.  The bass extended and the total sound improved significantly.  I occasionally make bass adjustments depending on what I am listening too.  There is nothing like listening to the 19812 Overture with canon and having the bass turned up and over emphasized!

If you could swing it you might want to look at this JL CR-1.  I did not see any SPL Crossovers available used in the US.  I highly recommend an active crossover if you have dual subs (or more).  

https://www.usaudiomart.com/details/650175851-jl-audio-cr-1-crossover-free-shipping-in-conusa/

Thanks so much. I will explore that avenue and do some research. Much appreciated. Robert