What tube pre-amps pair well with Pass amps?

I have used ARC Reference 3 with SMc DNA 1 with great success. So, ARC Ref 3, 5, 6 and the SE versions should do very well. Perhaps other 6H30 tube pre's would do as well, like BAT for example. Be careful with impedance matching. PASS are terrific amplifiers for your stated purpose. Good luck. Enjoy.

One thing about balanced operation is that it is meant to help reduce the effect of the interconnect cable. If you've ever auditioned interconnect cables and heard a difference you know what I'm talking about. Audio engineers frequently poo-poo the idea that cables can make a difference, but they are using balanced lines and equipment that supports the balanced standard so they can come that conclusion not realizing that they are talking apples and oranges.

But Pass Labs are balanced input, so if you want to get the most out of both the amp and not have the cable be a big system influence, your investment in the amp will be best served by a preamp that supports the balanced line standard (also known as AES48). Not surprisingly, most high end home audio equipment does not support this standard! That is part of the reason there are exotic and exotically-priced interconnects (balanced cables need not be expensive to sound really right). Its a simple fact that if the preamp does not support the balanced standard, the interconnect cable will be part of the hidden cost of getting the system to sound right.

In a nutshell, here is the standard:
1) pin 1 is ground, pins 2 and 3 are the signal; pin 3 the inverted form of pin 2

2) The signal does not reference ground (instead pin 2 references pin 3 and vice versa) as that can cause a ground loop. This practice also means that the shield of the cable is not used for anything other than shielding and so in this way is fundamentally different from single ended connections!

3) the preamp should be able to drive low impedances with ease and no loss of low frequency bandwidth. 'Low impedances' means less than 5,000 ohms.
If the preamp cannot do these things you'll be hearing cable artifact and you simply won't get everything out of the amp as a result.

Hay Atmasphere, thanks for bringing that point up.  May I respectfully ask for the names of some pre-amps that meet AES48?  As you can see, I'm on a steep learning curve and I know I have a lot of work to do, so any further guidance/direction is appreciated.

Yabe, do  6H30 tube pre-amps meet the AES48 standard, or is the tube topography considered separate from the line output?  With  impedance matching, I assume your talking to pre-amp/amp impedance?  Can you expand on what your looking for?  FYI, I may be misusing some terms.  If so, please correct me.  TIA.

I have to disagree with Atmasphere on two points:
1. I have a fully balanced Pass Labs XA60.5. The cable does make a difference.
2. I have two high quality Cary preamps. Cary SLP-98P Formula 1 mod, which is single ended. Cary SLP-05, which is fully balanced, but not upgraded. The single ended preamp sounds better with the Pass than the balanced in my case. That is why I am upgrading the SLP-05, for better SQ.
The bottom line is that preamp quality is more important than using the amp in the balanced mode.
Btw, make sure that if you use the Pass Labs in single ended mode, to insert the shorting jumpers, so that the unused half does not introduce noise.

One caveat to my points.
My preamps are very close to the Pass amps; so the interconnects are short. With a longer interconnect run, the balanced connections may possibly be superior.

@billtro Ama-sphere (unsurprisingly) makes preamps that conform. I presume that Pass does as well. Unsure unfortunately about other brands, perhaps some others will know of some options...

Pass Labs whether due to technological or marketing reasons promotes their “super symmetry” as a selling point. This might be best used in balanced mode. Some of the Pass Labs amps have a somewhat low input impedance.  If wanting to use tubes, I suggest considering the Atmasphere and Sonic Frontiers pres.

@cakids   +1 !

The bottom line is that preamp quality is more important than using the amp in the balanced mode.

@cakids
I have Pass Labs XA60.5 amps. My preamps are both Cary Audio - SLP-05 and SLP-98P F1 version. The modified SLP-98P sounds a tad better...

Last year when I was demoing different amps again, I asked Nelson about my own Cary SLP-98/F1 tube preamp pairing with a Pass .5 or .8 amp. He shared having many customers running them already. Guess it’s true :). A buddy with the XA-25 amp also tried with his own SLP98 preamp and liked the pairing a lot. We agreed it was not quite like his strapped triode tube amp, but really nice and musical!

May I respectfully ask for the names of some pre-amps that meet AES48?

Well ours do of course. Also Backert Labs, if you get the version with an output transformer to do the balanced output. Most preamps that use an output transformer in that manner should be able to support the standard- and it won't matter if the internal circuit is balanced or not.

I have to disagree with Atmasphere on two points:
1. I have a fully balanced Pass Labs XA60.5. The cable does make a difference.
2. I have two high quality Cary preamps. Cary SLP-98P Formula 1 mod, which is single ended. Cary SLP-05, which is fully balanced, but not upgraded. The single ended preamp sounds better with the Pass than the balanced in my case. That is why I am upgrading the SLP-05, for better SQ.

This is actually a really good example of what I was talking about. The Cary does not support AES48- any preamp that has RCA and XLR outputs, and does not need a switch to use one or the other, very likely does not support the standard, and so you will hear differences between cables that can be pretty profound.

One caveat to my points.
My preamps are very close to the Pass amps; so the interconnects are short. With a longer interconnect run, the balanced connections may possibly be superior.

The benefit of balanced operation really does not have much to do with the length of the cable. The benefit can be there even if the cable is only 6 inches.

I am using the Pass Labs XA-60.8 amps with the Pass Labs XP-22 preamp in balanced mode and I can only say the musical presentation is outstanding in every way. It is very musical and not in the least anemic or lifeless. I have not heard any other Pass Labs preamps, but what I am hearing now is the best I have ever had in my system. 

Pass Labs whether due to technological or marketing reasons promotes their “super symmetry” as a selling point. This might be best used in balanced mode. Some of the Pass Labs amps have a somewhat low input impedance.  If wanting to use tubes, I suggest considering the Atmasphere and Sonic Frontiers pres.

@unsound If you're curious, here's an article where Nelson explains what the term actually means... https://www.passdiy.com/project/articles/super-symmetric-amplification

@cal3713 , Yes, thanks. It’s been a while since last read. ...Hence, my suggestions.

I stated earlier in this thread how great my system sounds with a Pass Lab preamp and Pass Lab amps. I have now heard the Aric Motherlode II in my system and it sounds amazing! If you want a tube preamp you should definitely talk to Aric. I ordered one today!

+1 @jake18aa
I felt the same when I matched up my Pass XA25 with an Aric Audio preamp! This combination makes a wonderfully musical, holographic, and natural presentation of the music that I find extremely satisfying!

Atma-Sphere MP-3 Pre-Amp fully loaded will give you about 80-85% Of the Mighty MP-1 Performance.


I used to own VAC pre-amps before they are nice and warmer sounding but overall i still like the Atma-Sphere better. 

When comparing Focals and any amp, pay particular attention to the mid bass.

They tend to be above-average demanding and therefore suppressing output this region. There's no right answer, you might like it suppressed, giving you a built-in loudness curve or matching better with the room.

Given this combo, old school CJ or Sonic Frontiers.

billtro
What tube pre-amps pair well with Pass amps?

Many don’t work with quite a few Pass amps as many Pass amps are low input impedance, and a lot of tube preamps are high’ish output impedances
You need to look at output impedance v input impedance 1 to 10 ratio or more for good impedance match. Otherwise it can start to become a voltage divider and "can" squash dynamic impact as well as output level.

Cheers George

I've often wondered about this, for different reasons like the allure of tubes etc.

I'm run the Pass Labs XP-22, XP-17 and the XA60.6s with an analog front-end only. I recently put in a distributed bass array and altogether I'm blown away and quite happy. Yet...

Curiousity and interest got the best of me and I reached out to Pass. Here was their recommendation for tube pres: Atma-sphere, BAT, Conrad-Johnson.

I'd like to know what the OP decided to do. And any other continuing thougths.