amp suggestions for Aerial 7b

just starting the process of upgrading from my krell s-300i integrated to separate amp. listen to rock 20%, alt-rock 40%, jazz 20% and classical 20%. need something with plenty of power as these 7b's aren't the easiest speakers to drive. 7b's are rated at 6ohms but i've been told the behave more like a 4ohm speaker. thinking *minimum* 250 watts into 8ohms with double down capability to really make the Aerials sing. i do tend to listen to music on the loud side of things. also....something that can drive almost any speaker in case i upgrade the 7b's next year(like i plan to).

will be using the amp exclusively with my ps audio perfect wave transport and perfect wave dac. gonna try the PWD as my pre-amp for now. will consider adding a pre-amp later if i don't like the pwd as a pre. will be buying used and budget for the amp is roughly 4-5k max. (prefer single box but will consider mono blocks also). i'd be more then happy to spend less though.

have focused on room acoustics for the last 2 months and think i have a good foundation now. acoustic panels, corner bass traps, carpet and heavy drapes really seemed to help with the forwardness my current system use to have. room is 15x23.

want something as neutral as possible with good detail. not looking for "warmth" but don't want harshness either. smooth highs and tight slamming bass are a must and again...detail.

so far the list is short. Pass X250.5, older Levinson 335 or 336 and maybe a Mcintosh of some type...402 maybe??. comments on these 3 amps with the 7b's are welcome as are any other suggestions. since i'm buying used, i won't be able to do any in home demo's. will have to make a decision based on in store listening.

thank you

Lev