WARNING AN ATC USER RESPONDS :)
I've heard Wilson WP's in a very expensive Levinson setup (390S, preamp, monoblocks) and it sounded very nice.. but it was four times as expensive as the active 50's I have... maybe it was the room, maybe it was the speakers, but I prefer the 50's.
As for using valve power amps with passive ATC's - I'd say forget it. These speakers love power, and you'd be looking at 100's of watts. Moreover, just about everyone agrees the ATC's should be active..
As for pre-amps, front ends, interconnect and mains leads (and power conditioners) your going to find that ATC don't play the Audiophile game. ATC recommend Belden interconnect, I don't think they recommend special mains treatment, and I beleive the opamps used in the active crossover would give most audiophiles apoplexy.
I've used my 50's with CD players and preamps on a spectrum of prices and the systems sonic signature is totally dominated by the room and speakers. I can recommend ATC's preamps (I happen to own both), but they are rare in the US and the cheaper CA2 is truly excellent for very little money.
I've run my 50's direct from a Benchmarkmedia DAC1 and they sound superb. It's possibly the best value for money system I've ever heard.And is not beaten by the Levinson 390S direct (which I also own..)
As to why no magazine has reviewed them. Well, widescreen review were very positive about the 150's. But truth be told ATC are a small company that in the last couple of years have become much more visible in the UK with the excellent active 10's, passive 7's and 12's - they've probably got their hands full over there :)
Moreover, they are a small company without advertizing revenue, so there is no "incentive" for review by the US magazines - the range has been well received by the UK press. The active 50's and SCA2 preamp were reviewed in HiFi+.
Finally, ATC have a solid reputation in the pro world - they don't need accolades from the highly subjective hifi press, or the desire to put up with the audiophile BS.
Here's a copy of the widescreen review article..
Finally, reading reviews is pointless. You need to hear a pair, no matter what any reviewer says (even someone with charisma like Art Dudly) it's your ears that matter. Also, 150's, or any speaker with that level of bass extension and power, needs to be tried at home, otherwise you might find yourself wanting to take a bath with an electric fire...