First Watt SIT-3 preamp pairing advice


Hi There,

I have Nelson Pass's First Watt SIT-3 power amplifier. I am using a ~15 year old VAC (Valve Amplification Company) Standard Preamplifier with NOS Telefunken 12AU7 and 12AX7 tubes for the 2 stages. I am looking to upgrade the preamp and am considering the Passlab XP-12 or the Linear Tube Audio MicroZotl MZ3 preamp. My impression is that both preamps are fairly popular when pairing with First Watt amps. Anyone here have paired both these preamps with the SIT-3 and can provide impressions that might help me decide? If there is 3rd option that you like very much, I am all ears too. Thanks in advance for any advice.

Andrew
longinc

I have the SIT 3 parked with a Freya+ and Soliloquy 6.3’s 89db (2.5 way) bi-wired speakers. I’m quite certain the more expensive preamps listed make noticeable improvements over the Schitt preamp but I’m satisfied with the gain level of the Freya at my price range in combination with the tube friendly 6.3’ and SIT3. Got a steal on some GOLD Wireworld interconnects (probably overkill for my system) and maybe that helps mend the trio together keeping the holographic warm-glow but well retaining the separation of the highs, thumps and mids. Happy listening!

I have SIT-3 and SIT-2 as well. Speakers are cube audio nenuphar, 92 db efficiency.
After a long debate between me any myself i bought a pass xp-22. It simply rocks, and can drive the SIT-3 (which is the more picky amp here) to its potential. 
I would suggest either the xp-12 or the 22/32 depending on budget. The design of the pre is very flexible to work with the widest range of sources and amps
HI @mrubey , Nice! and thanks for sharing your journey. Looking forward to hearing your impressions of the MZ3 paired with your SIT-3. I would reach out to Nicholas at LTA, he is really responsive to questions.
Hi Andrew, 
I have a SIT3 currently paired with a "The Truth" passive preamp with photocell attenuation.. My speakers are Cube Nenuphars (92db, 6ohms). I have no gain issues at all playing digital but analog is my primary source. My analog front end has plenty enough volume with only one or two exceptions of records that are relatively quiet pressings. The recent pressing of "Abby Road" being one. I've been very happy with "The Truth". It's about as pure as it gets. But I am feeling the itch to explore other possibilities. I had a MZ2 for a short time once when I was using a 2A3 SET amp. The ZOTL did not pair well with the SET. It made beautiful pure tones but the sound stage and 3d dimensionality of the 2A3 amp went flat. Still, it was an amazing headphone amp and I miss it. I'm certain it would have been completely compatible with the SIT3. I am seriously considering the MZ3. I would like to buy another MZ2 and save the cost difference for other things. But the word is that the sonic delta between the MZ2 and MZ3 is more than worth the additional cost. The SIT3 and Nenuphar deserve a preamp of equal endgame caliber. LTA says the MZ3 is the full realization of the potential of the ZOTL circuit.  I am certain there are other vastly more expensive preamps out there that would be appropriate for the SIT3  but  I'm not sure *any* more costly pre would actually be better in my system. At least I'm willing to see if this is true.
So yes, I intend to purchase an MZ3.
The MZ2 has more air and transparency. I would agree with zm's characterization of the MZ2, but it still has that tube liquidity. I do think the other 2 choices are good pieces, and I still haven't sold my Supratek Sauvignon . I've been thinking about building or buying a Don Sach's phono stage.  My MZ2 has remote volume control and an external power supply, they are both options and it is considered a Stereophile A rated headphone amp. With  both options it costs a little over 2K. The pictures of the MZ2 don't give the fit and finish of the unit justice. I believe the case work is done by Fern & Roby. It is very well built.
I was going to purchase the Pass HPA-1 but it doesn't have a remote control. As I'm writing this response, I'm listening to Ronnie Earl and I feel like I'm in the studio/hall with them.
Thanks @cal3713 for your impressions! Very helpful. And i tend to agree that anyone that spends time on creating a highly engineered outboard power supply likely has a good product. I am in the camp that a good portion of the sound (quality) of a piece of audio equipment comes from the power supply. 
I have to put another vote in for the Supratek.  I have the Cortese LCR.  I drive Rethm Saadhana (100 dB sensitivity).  Cant say enough about the sweet sound.  I prefer analog, but do listen to a lot of Qobuz/Tidal due to me limited vinyl collection.  My ExoGal Comet DAC does help keep streaming more analog sounding also.
And value of Supratek is outstanding!
My advice would be that if you are looking to land on the cooler side of neutral rather than full-on classic tube bloom, the LTA would be the better choice.

@zm I have read this so many times from so many people that I take it as fact. 

The LTA is great, but falls "on the cooler side of neutral" as you state.  If you're looking for warmth, it's not the place to go.  In that case the Don Sach's is a good candidate.  I have owned and loved one.  Note that its sound is heavily determined by the the output capacitors and tubes used.  You can read on my system page for some information in those regards if interested.  My speakers aren't naturally warm (accuton drivers), so adding a cool-leaning preamp is a no-go for me. 

I suspect the Supratek sounds similar to the DS, but gives you a higher gain option, and has an external power supply which is a + in my book.
Also want to second what Nelson Pass said, and which @vinpic highlighted earlier in this thread: the SIT-3 behaved like a different, happier amp when I wired resistors in parallel with my 8 ohm speakers to drop the load the amp sees down to 4 ohms.  I felt kind of dumb trying this with 8 ohm speakers, and wasn’t expecting much, but it definitely improved the overall presentation, which was already excellent. A fun, inexpensive tweak to try.
@longinc My speakers are 95db Omega single drivers, and in my system/room and my listening tastes, I have no gain issues using the MZ2 with the SIT-3. Others may have different experiences, of course.

The Don Sachs is an excellent preamplifier, but after extensive A/B with the MZ2, the different strengths and weaknesses of each are immediately apparent. Both excellent, and more than anything I think the choice comes down to personal tastes/preferences rather than any objective sense of which is “better”.

My advice would be that if you are looking to land on the cooler side of neutral rather than full-on classic tube bloom, the LTA would be the better choice. And for bass management, to my ears, the LTA is definitely much cleaner and tighter. Again, all a matter of taste.
Check out Aric Audio. Aric builds a a couple great 6sn7 tube preamps. Variable gain output up to 20 dB. Call him and discuss your needs.
@coachpoconnor - thanks sharing your comparison. Why is the LTA the clear winner in your comparison of the 2 preamps?
Thanks @vinpic! Your notes are super helpful - thanks for sharing. And very nice speakers you have there!
I have the Supratek Sauvignon and a LTA MZ2, I have used both with my Pass XA25. The LTA is the clear winner in this combination.
300W RMS !
for any application.

 Those little baby amps look, sound nice, but will clip at every crescendo and drum solo!
For what is worth 2 notes I had stored in my files regarding the SIT3.  Hope it helps 

Regarding the SIT3, an important point to note is that it has an extremely low gain (for a power amp) of only 11.5 db. Power amp gains are typically in the mid to high 20s.  

Consequently it can be calculated that the SIT3 will require a single-ended input (it does not provide a balanced input) of about 3.2 volts to be driven to its maximum power capability of 18 watts into 8 ohms. If a digital source having a volume control is used without an active preamp it will almost certainly not be able to provide that much voltage, even with the volume control at max. And in many and perhaps most cases vinyl or other analog sources won't be able to do so even when used in conjunction with an active preamp.

I considered purchasing a SIT3 recently, but that factor made it a non-starter for my system. I went with a Pass Labs XA25 instead, which I have been delighted with.


Regarding the optimal ohm rating for the SIT3, the following is from Nelson Pass.

“The most popular impedance for the load is 4 to 8 ohms, which is the region where it measures best, and there is not a lot of difference between those two numbers. At lower, we see increased distortion, and at higher impedancethe distortion numbers don’t go up, but there is an increase in higher orderharmonics. It’s not a big deal, but you can play with this by putting some resistance across the speaker. Typically people play with resistor values from 8 to 25 ohms, and since resistors are cheap I recommend that you get several values to try. The type of resistor is not critical, but should be ratedat 5 watts or more.”

I have Avantgarde duo XD at 18 ohms. I use a Zu Audio 10 ohm resistor across my terminals to give the amp a resistance rating of 6.42 ohms calculated.

Works wonderfully.


Hi Longinc - using Cube Audio Nenuphars 92db 
a marriage in heaven with the sit3 🍾

Hi @vinpic,

Thanks for your input on the the MZ2 preamp. What speakers were you using when you had the MZ2+SIT3 in your system?

Andrew
I have the mz2, a great preamp overall but not capable of driving the sit3 to its full splendor.  Dynamic range & bass mgmt arr simply not as good as higher gain pre-amps.  In my stable the VRossi L2i does a great job, the preamp section of a Lumin or Mola Mola dac is amazing as well (the latter set @6V)
I'll put another vote in for the Supratek.  Everything Tvad said is relevant and there are literally no bad reviews.  
@zm thanks for your input. I read good things about the LTA MZ2 and MZ3 pairings with the SIT-3. Like you i do like clarity, transparency, speed, timbral accuracy of the SIT-3. Tad bit of tube bloom is fine but too much not so (which i assume is what you were experiencing with the Don S). Hence i was leaning the way of the MZ3, but wasn't sure given its ~10db gain and my speakers are 89db sensitive. I don't listen loud but my current preamp's gain is 24db and my knob is usually (depending on the recording) between 930am and 1130am. What speakers are you using with this setup?
Thanks @jayrossi13 for your input. My speakers are a Chapman T7 (4 ohm, 89db sensitivity). My moderate sensitive speakers is giving me a little pause because the other options i am considering (linear tube audio and pass labs are ~10db gain). Did you consider others and how did you land on the Supratek Cabernet?  
I use the LTA MZ2 to drive my SIT-3 with superb results. Very good synergy between these two units. The MZ2 is not a gain monster but I have no problem driving the SIT-3 to a happy place. The SIT-3 really showcases the unique blend of tube liquidity and solid state speed that the LTA units offer.

I also have a Don Sachs Model 2 that I use with the SIT-3. The Sachs sounds very good, but in my system I prefer the MZ2 paired with the SIT-3. The Sachs unit is more romantic sounding and has more tube character, but I miss the bass and clarity I achieve with the MZ2-SIT3 combo.

Edited to note that I didn’t read closely enough to see you were asking about directly comparing the MZ3 with the Pass pre; I haven’t heard the Pass; sorry about that.
The Supratek is a great match for the SIT-3. I had the Cabernet DHT/6SN7 model, which has high gain. The gain is also adjustable, which is great for really dialing in the sound and getting rid of idle hiss on high sensitivity speakers. 

What are your speakers?



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Thanks @tvad ! I will look into the Supratek and looks like folks when considering the Supratek are also considering the Don Sachs preamp. So many choices! Have you paired the Supratek with the Sit-3?
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