Pass Labs users. Next upgrade?

Null1, I have no room treatments and I don't use a power conditioner. I have my system in the main living area. I would be afraid for my personal safety if I attempted to make my audio presence dominate my wife's decor. I don't have problems intergrating my speakers and subs.. they match seamlessly great bass!... higher mids and highs can be harsh though at higher spl's.
I am an Electrician. At one point in my life, back in the disco era, I ran circuits for Live and D.J. music systems. So I have 2 dedicated 20 amp circuits. One for Amplification and the other for source componets. My neutral and mechanical grounds are not bonded (they are grounded independently)I also use audio quailty outlets( all copper, no brass parts) My Amp circuit is run W/ #10 solid copper wire(less voltage drop during periods of higher demand). They are as quiet as any residental circuits can be

Ditch the Adcom for about any preamp, but the Pass X-1 or about any of the Audio Reseach preamps would be great choices. I'm sure the 350.5 is better, but the 350 is a very good amp. The Adcom preamp is a major limiting factor in your system.

9rw, Are you talking tube or solid state when recommending Audio Research? There are so many A.R. pre's on the used market. What have you used w/ your X-350? If you are not familiar with my Audio Physic Virgo's they have a similar sound to Magnapan and other Electostatics...(but are not). They just tend to get a little sharp in the highs.
I'm really surprised the Adcom does't match up better with the Pass Amps. I had the X-150 first, with the same results. I believe Wayne Colburn of Pass designed the Adcom 750 and is just a less complicated design than the Pass Aleph P.

Gandme: I used a Pass X1 and ARC LS25 with my X350. Both were good, but the X1 was better -- in my opinion. It had better dynamics and better extension (highs and lows). As for ARC preamps, I was mainly referring to the tube preamps, but the old LS3 was a nice preamp, too.

Thank you all for your help! I've narrowed my choices to an X-1 or X-0.2 (possible trouble in paradise W/ the 0.2 price). It probably makes sense to stay with Pass products for the synergy. The next logical upgrade would be the X-350.5. The X-350 is the best Amp I've had in my system...so I don't know why I'm even discussing replacing it! (as my wife likes to point out,"It's never going to stop, is it!"). I wish I could A/B this stuff in my living room with several other pairs of ears and a glass of Red!
Cheers to all, Greg