Pass X150.5 vs. X250.5

Kind of figured there was not much to be had by going to the 250.5. The speakers are average efficiency, around 6 ohm if I remember correctly. The room is roughly 13x18x8, so about average too. Ww carpet on floor, some absorbers at first reflection, no real furniture to speak of other than 2 cabinets on side walls. Using Pass X2.5 pre, all balanced Acoustic Zen Matrix Reference, Kimber 12TC double bi-wire to speakers. Playing with speaker position and tilt forever! Guess that is the direction to go for now!

Ok, meter does not exactly BOUNCE, but the does move up from its static position at 9:30 to about 11:00 when it is at it's loudest. Doesn't really seem TOO loud, but that's a matter of opinion, unless it's causing hearing damage..... Anyway spoke to the folks at Pass Labs today and they said I COULD be running out of power, maybe the X250.5 is the way to go but borrow one first and see if that changes things. Sensible, those guys. They felt that meters hitting 11:00 was close to running out of power. I was kind of surprised at that, but who'd know better than them? Anyway they also suggested a change of wire to the upper section of speaker an another way of taming any harshness, but I don't think that would really help based on other cable I have used in the system. Just as an aside I originally had a pair of Aleph Os, but I sold them for the 150.5 to get more detail and dynamics, and that was exactly what I got. Another reason for looking into the 250.5 is that there are currently 2 in NJ on the list, and that's where I am, so It'd be very simple for me to buy one of them. Thanks for the info so far guys!

Interesting theory about the room. You could be on the mark there as there are absorber panels between the speakers on the front wall,and a panel at each first reflection, but nothing behind the listening chair and nothing on the ceiling, although one can go to far there too. Thought the live end-dead end theory was at work, but I'll try some absorption in the back too. Also understand where you are going with the class A amps. I was thinking in terms of total power, not class A power when I thought about the 250.5. I'd probably need at least an XA 100.5 to make it work in class A, but that is WAY above budget.

Update to the problem. As hard as it is to believe, I changed the power going to my pre-amp from a conditioner that had my digital front end plugged into it to one that only had an analog device plugged into it and the harshness was almost completely eliminated. This even though the MFR said the outlets were isolated. Then tried heavy curtains on part of back wall, but that made things too dull, so guess I'll live with the considerable improvement the conditioner switch gave me, until I can get some diffusion for the back wall and try that. Thanks to all! And keep the ideas coming.

Seems like separate is absolutely the way to go as far as power is concerned. Just wish it would be easier to get a dedicated line into the room, but there is no floor access to the main panel as there is a slab floor. Ceiling is floor to second level. Like I said though , major improvement with separate power sources!