PSB Synchrony One Speakers and Pass XA30.5 Amp

Did the PSBs ever have the vitality you want, driven by any other amp?  If so you know they can do it,.  Now you have to decide whether you want to design the rest of system to get that out of them.  I went through that with some Focal Electras and was quite happy with the result.  It literally to years of trial and error to get there  though.  If you haven't heard them do it in another system then I would ditch the PSBs, and go on the "perfect speaker" hunt.  The bane of all audiophiles known to take down even the high and mighty.

I agree that the XA-30.5 may not be the perfect amp for those PSB speakers. However, there are other factors at play. Pass Labs gear tends to be warm and musical, so combining a Pass preamp with a Pass amp may be too much warmth and not enough detail.
Many Pass amp owners use an ARC preamp, like myself. The ARC provides a bit of speed and resolution to the musicality of the Pass amp.

That said, I'm still not sure that the XA-30.5 is enough power to drive your speakers. My room is 24 (L) X 15 (W) X 9 (H), my speakers (90 dB, 5 ohms) are a bit more efficient than yours ( 88 dB, 4 ohms), and I am running XA-100.5's, which provide plenty of power. 
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.

mechans brings up a good point. Have the speakers ever had this "liveliness" that you are looking for? The speakers may benefit from more power, but I find it hard to believe the XA30.5 is solely responsible for the issue. Stereophile's review on the amp measured 130 watts before clipping into 8 ohms, 195 watts into 4 ohms, and over 330 watts into 2 ohms. This is a beastly 30 watt amp. 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?

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.