Looking at these specific preamps give me your opinions

@invalid Krell had over 20 employees, not 1 or 2. I understand this can happen with any company but its less risky with larger ones. 

@brbrock  - I heard them with the Blackbird monoblock prototypes at the Pacific Audio Fest last summer in the Spatial Audio room. The system sounded very clean and detailed with excellent sound stage. They didn't sound overly warm or have sloppy bass, but were smooth, balanced, and easy to listen to. Based on what I heard, I decided to use a similar topology in the DIY preamp I am currently building. 

I used to own the NX-Otticas (now with my son). I upgraded to Line Forces and also have GR OB woofers (a pair of quads in my case). I think the Raven preamp would sound very nice in your system. 

@willywonka that can happen even with larger companies, look at Krell right now.

I'm a sucker for small boutique companies (1-3 people) like these but always worry what will happen for my support/repairs of their product after they close their doors or pass! Hopefully they will outlive me!

@jaytor You say you have heard the Raven.  Did it have tube sound?  What was your thoughts on soundstage etc.  Was  it matched with a tube amp?

I heard from Spatial yesterday after inquiring about the Raven - what I've decided to purchase - and they have 1 that isn't spoken for in the current build cycle. Those are supposed to be ready for delivery in about 8 weeks. The next build cycle is targeting a December delivery and that works better for my timeline. Anyway... FYSA if anyone is ready to to buy now, better hurry before it's gone.

The Raven

I am leaning towards the Raven.

I haven't heard the Raven, but what I've found with the LTA MicroZOTL is that the sound quality is greatly effected by tube selection. Mine originally had Trigon tubes which honestly sucked.  Telefunken and Siemens tubes were tons better.  Brimar Yellow T are also good, but on the warmer side. 

I heard the prototype Raven as well. That’s what I’d choose. 

The Raven.  I heard the prototype and was able to compare it to the LTA.  It was an immediate "no contest."  And the final product has a couple more improvements that Don Sachs, Lynn Olson, and the guys at Cinemag used to put on the final touches.  This was a great collaboration between some great names in audio, and it shows.  

No shortage of fellow audio enthusiasts who own and have provided their candid and detailed thoughts on Aric Audio tube gear...myself being one of them. Take a few minutes and call him. His build experience and customer service is matched by only a few in this esoteric hobby of ours. 

I am leaning towards the revelation.  I would love to see someone review it.

Always wanted to hear the VRE-1C.

Of those preamps, the Raven preamp without question....but I'd add Aric Audio preamps to the mix, especially the Motherlode or Motherlode XL

Revelation Audio Raven would be my choice from your original list. No question. A highly regarded designer who has keenly refined the circuit topology and parts list. These things are important. Nay, critical, essential.

People often refer to the weight of a unit as a sort of shorthand for indicating the quality of the design. And that can be useful.  But it is a rather crude measure.

I'd be looking for point to point wiring and the use of 6SN7 tubes or similar (6J5, 6SL7, for instance). These tubes are regarded as classics for a reason. That is, they sound really good.

@brbrock - +1 on the LTA Microzotl preamp with the level two upgrade offered by LTA. Fantastic preamp! 

Take a look inside each of them and then tell us what you see?  Parts, transformers, AC chokes, capacitors, resistors, volume control, and what designs they are.  Once you begin to look inside and learn about design, you decision will be come much easier and you will understand what makes sound quality.

Happy Listening 

sls883:  Thanks!  The Telefunkens might be too bright in my system but I will listen a bit to how the LTA sounds from factory, then jump for those or the Siemens, depending on the effect of the LTA pre to the overall sound.  Love detail but don't want too bright. Cheers.

I own the PrimaLuna EVO 400’preamp. Very pleased with it. Very quiet and great sound stage. It’s a dual mono design and right at 60 lbs. A reliable preamp. 

@gregjacob I'm using the same Telefunken ECC801S.  They are the most detailed and best sounding in my system. A friend thought they were too bright in his system. The Siemens ECC801S are very good, but a hair less detailed. A fair bit less expensive, though.  The Brimar Yellow T are nice and warmer sounding if your system is already on the bright side. 

cbrez   Thanks for the tube suggestions!  I'll check in with Brent.  Of the tube swaps, which set do you feel made the most audible improvement?   I might try one set, then add changes from there...  Thanks.

@gregjacob I replaced the 12AT7s with Telefunken ECC801s. I replaced the 12SN7s with CBS/Hytron VT-231 per a recommendation from Brent Jessee. If you use 6SN7s as a replacement, you just have to slide the internal switch in the pre to 6V. The tubes were not inexpensive, but well worth it in my opinion. The difference to me was amazing.

Perhaps you should take a look at VAC preamps.

@cbrez ​​​​​​

I bought my MicroZOTL preamp lightly used and a little over a year old.  The previous owner said it came with Trigon 12AT7 tubes. I tried them and didn't like them.  He had purchased some Telefunken tubes {not cheap} and I bought them with the preamp.  I've also tried Philips, Siemens, and Brimar Yellow T.  Siemens came in a close second to the Telefunken. These are all 12AT7 type tubes. 

The Townshend Audio Allegri Reference Passive preamp is very good. Not true balanced though but that keeps the circuitry to a minimum. 

cbrez: What tubes did you decide on for your upgrade replacements?

Of the preamps listed, I can comment on the LTA microZOTL, as I have this in my system. I think it is a spectacular preamp. Not warm sounding, but very natural. Excellent dynamics and very open sounding. I run it with a Pass amp and could not be more pleased.

I also just rolled in some new tubes to replace the stock tubes it comes with. I thought it sounded good before, but it was next level afterwards. Better top to bottom extension, more organic. A real winner for my system.

+1 @pindac

Raven preamplifier Got one (need to update system page). Full stop. Done.

If you stream or will be adding one you could think about the Grimm MU2. Stream/DAC/Pre/Roon core all in one. While I’m all for separates except not with the stuff Grimm makes.

Backert Labs, it’s been the preamp of my dreams! The love affair continues. It’s quiet, detailed and though neutral, there is real magic in how it has made my 300B’s sound with O96’s. You can’t beat it!

Knowing the story behind it and the people involved with the design and implementation I would most certainly look into the Revelation Raven. My suspicion is that it's truly superb.

Charles

Really depends on what sound characteristics you’re looking for.  That said, I also have a fully modded DNA 0.5 and I’d do a trial of the Raven without a doubt, but that’s me.

I just figured out recently that LTA uses technology from berning and Steve McCormack with SMC helps design berning amps. So 3 of the 4 on the list are related in some way.

I have a LTA MicroZOTL preamp.  I had two different conrad-johnson preamps before that.  I'm using it with single ended interconnects to a Coda solid state amplifier.  I'm very happy with it.  I thought I'd miss the warmth of the cj preamps, but I really don't. I feel that it's better than the cj. 

I have, and really enjoy the PS Audio BHK preamp. It has five inputs, and each input has both balanced and RCA connections. You could actually hook up 10 devices at the same time, so long as you only played one (either the balanced or RCA) at a time per input. It also has both balanced and RCA output, and I have them simultaneously attached to a power amp - the balanced to the Zesto, the RCA to the Coincident. Then I can choose which one to use by only moving the speaker cables in the back, which takes mere moments. 

It has a tube input, and mosfet output. When you roll in different 12au7's you can really hear it - I have enjoyed shaping the sound by thoughtful tube rolling. As a bonus, it has a very nice internal headphone amp that powers my Audeze headphones with ease. 

Anyway, that is the one that works for me... 

also listen to Ayre.

Add Audio Research and Rogue to your list. 
Rogue RP1 is an enormous bargain and a serious competitor. 

@brbrock The 'Revelation Raven tube preamp by Spatial Audio', has a substantial Pedigree, and is also the work of individuals who have taken the Design Intent and selections made for the circuitry that is beyond usually discovered in the main stream manufacture arena.

Valve Circuit Enthusiasts are extremely fortunate to have this model as competitively priced option.

I would love the chance to be seated om front of one.

For the Short List it is well worthwhile to attempt to have a experience of one in use.