Rega Elicit R w/PSB speakers

Fishing716,
It really isn't a matter of how many watts an amp is at 4 ohms. 50 watts is capable of decent volume levels with synchrony one's... (88 to 90db sens)I'd probably want 100 minimum.
The problem is what happens to an amp trying to drive a 4 ohm load... The better an amps power supply is the closer that amp comes to doubling its power from 8 ohms to 4 ohms, that is the reason for the wattage recommendations. A good power supply sounds better and your amp won't crap on itself trying to drive your PSB's.

Sorry Fishing716,
I really should have mentioned. If you are a rocker, or listen at relatively high volumes for long runs of time, your Rega might have a problem, but if you listen at reasonable levels for an hour or two on occasion and aren't driving the bass hard. Your Rega should work fine... I don't want to mis lead you though, other amps that have proper power supplies may or may not sound better than your Rega, depends on the amp and your listening habits.

I listen at reasonable levels
Classic Rock,bebop Jazz & Classical
I'm leaning toward Bryston Seperates
2.5 & 17
135w into 8ohms

That Bryston only has 180W into 4 ohms. I think a Bryston would be a good amp to drive PSBs, but remember the Synch One's impedance drops below 4 ohms, so I would think it might need higher power; it depends on the size of the power supply of that amp. If I remember correctly, you were missing the fullness of bass with your other amp.
But, I'll bet the 3BSST can drive your Synchs.

I'm auditioning 2.5 w/17 preamp coming next week..
I'll report back if it provides adequate power/bass