PSB Synchrony One Speakers and Pass XA30.5 Amp

Are you getting 3D imaging and wide soundstaging? You should be with that amp.
Lastly, what are your speaker cables?

lowrider57, not really remarkable imaging or soundstaging (I've had better in another system in another house.) Space constraints limit the speaker-to-front wall distance to less than 2ft. I sit as far back as I can so increasing that distance means even nearer-field listening. I do have them about 7ft apart, though, at least 2ft from the side walls. I'll try re-positioning. Speaker cables are Wireworld Equinox 7 (I also have Anticables Reference 3 which don't sound noticeably different from the Wireworld.)

Did the PSBs ever have the vitality you want, driven by any other amp?

mechans, I only tried them with a Hafler 9500 which didn't sound quite as good as the XA30.5 (even though it was much more powerful at 375W/ch into 4 ohms) so I sold it and kept the XA30.5.

If you seek greater liveliness, it could be an amp/speaker mismatch, in which case I would change the speakers, or it could be that you need a preamp with a little bit more life.

jmcgrogan2, this is what I suspect (amp/speaker mismatch) although I still have a pair of Infinity Renaissance 80 which also lack liveliness with this amp. They don't sound quite as good as the Synchrony One with this amp, though. This makes me think the XA30.5 is too warm of an amp. I'm thinking about searching for something else to try.

Have you considered there could be an issue elsewhere? Would you care to list your entire system? What is the source? Sometimes power conditioners can make a system sound dull. Are you using one?

tls49, my source is a dedicated NAS feeding a Squeezebox Touch whose digital outputs feed a PS Audio DL3 DAC (which drives the Pass XP10 preamp.) I use no power conditioning. I also have a Denon DCD1650AR CD player and I've tried driving the XA30.5 directly with that from its variable outputs (eliminating the PS Audio DAC and Pass preamp) and matters don't change greatly. I only decided to try this yesterday so I'm still auditioning things this way.

Thank you all for your comments. If I had to try another amp what might I look for? I don't do tubes.

Why change the amp? I suggest auditioning some speakers that are more efficient and are more neutral. PSB's are toward the warm side, which is not a good match for the Pass Class A.

I have heard those PSBs paired with Bryston monoblocks and they sounded quite dynamic and very musical. Aside from your room configuration - on that later,  your issue as said before could be a matching issue. Your space arrangement seems to suggest you have a ~14' open space behind your listening position which could be a problem. Your 16' ceiling is another potential culprit. Also, I had a very similar experience but with completely different components where I had a real long and narrow room with tall ceiling and I could never get the near-field set up work for me using basically half of the length of the room. I moved everything to a smaller (repurposed) bedroom - 8' ceiling but the same exact distances for near-field listening and it all came alive. Try some temporary room treatment, especially behind your listening position and see if it makes a difference. Finally, looking at the measurements for these PSBs, a large portion of frequency band operates in 4 or less ohms - particularly the area where most of the music energy lives so by all accounts these speakers are putting a high demand on your amplifier's power supply.

Why change the amp? I suggest auditioning some speakers that are more efficient and are more neutral. PSB's are toward the warm side, which is not a good match for the Pass Class A.

I'm willing to consider alternatives to the Sychrony One. What can be recommended in that price range, say, up to about $4k used? Has to be full range and good looking. And good with all kinds of music, but jazz, vocal and classical, especially. Ideally one known to match well with the Pass XA30.5.

Look for a more efficient speaker (over 90dB sensitivity), preferably 8 ohms, which rules out Dynaudio, Totem, B&W.
Kef, Klipsch, GoldenEar are efficient speakers that can be driven by tube amps and are more transparent than PSB. Even if you were to move to a more efficient PSB model, I don't think their warm sonics would match well with the Pass.

Perhaps, start a new thread and you will get responses from tube guys and Pass Class A owners who can recommend an efficient speaker that excels in jazz and classical reproduction.