Pass Labs amps questions

SO i started looking into Pass brand amps.  My room is carpeted movie theater of rectangular shape, 18 wide x 26 ft deep.  I'm currently running Audio Research 5SE into Mark Levinson 331 (100 watt RMS SS at 8ohms) then Dynaudio Confidence C4 speakers.  Although I love the sound this gives me, i feel it just doesn't have enough oomph!  For example, in order to sound "right" when i listen to the Eagles Hell Freezes Over DVD, volume is at level 60 on the 5SE.  Im not detecting any clipping at all nor does the Levinson get too warm.  I don't think its straining at all but not sure how to tell.  Its old and i just want to try and get a different or maybe see if i can get a better sound.  I am wondering what the audioafficianados out there would recommend or provide more info on with regards to the Pass Labs line up.  I am specifically wanting a pair of Class A mono blocks.  What falls in my budget is a pair of the XA200.5's on the Agon site here now VS a New/Demo X350.8 demo from Reno Hifi.   Would the X350.8 hold an advantage over the 200 monos with its additional 300 watts of power (C4s are 4 ohms)? I remember needing to double the power in order to move the SPL 3 db???.   If this were correct and given my room size, would this added power benefit my system? All in all would you prefer used pure class A less power or brand new class AB higher power for about the same price?  I'll sit and *listen* for your knowledgeable replies.  Thanks in advance.