Good Speakers with Pass XA30.5 Power Amp?

I'm currently using a Pass XA30.5 power amp (with Pass XP-10 preamp) to drive a pair of PSB Synchrony One. Cabling is all Wireworld Equinox 7 and room is about 12'(W) x 24'(L) x 12'(H) with speakers firing down the long dimension - although I can only sit about 7' from the plane of the speakers. I find the sound somewhat laid-back, i.e., lacking in liveliness and I'm constantly fussing over the sound of the system. I listen at very moderate levels to a wide variety of music, but typically jazz (vocals), classical and choral music - with the occasional reggae and pop fare.

It's been suggested to me that the combination of the Pass XA30.5 and Synchrony One may not be a good match so I'm soliciting suggestions for speakers that should work better with the Pass amp - i.e., a more lively presentation. I'd prefer full-range speakers at least the equal of the Synchrony One in resolution and frequency extension. My budget is less than $4k used.