Amp opinions- ATI-B&K-Pass Labs

Vienna Acoustic speakers are very transparent and sensitive to their source equipment. I would go for the higher end amps with them. If solid state is your bag, I would look at the Pass labs Aleph series as well. I like those better than the x series.
You might look at some rowland amps - like the concentra. Those tend to 'back off' a little and would be a nice match to tame the vienna acoustics a bit. Also, check out the Adcom 5802 and 750 preamp. The preamp is world class transparent, and the amp has a nice, forgiving nature. Nelson Pass did the base designs for both pieces.

Great speakers...

Abecollins:
I am trying to suggest components that are not an enormous step pricewise from what is already present in the system. I agree with stereophile giving the gfp-750 a class A rating. I had it at the same time I owned the ARC Ref 1 and the Pass labs Aleph P. It was considerably more transparent than the ref1 & almost as transparent as the aleph P. While I think the Aleph P and ref 1 do sound a little better, they were all in the same general category. Personally I think they are one of the best bargains in high end audio.

Sayas:
I don't think the alephs are slow at all. They are about the FASTEST amps I've ever heard (spectral is possibly a little faster). I've used mine with audio physic tempos, virgos and avanti's (all fast speakers). Usually with nordost cabling. I've also used them with magnepans, spica's and vandersteens. Did you hear them with big speakers ? I know that the aleph 2's did make my vandersteen 3's sound a little less authoratative in the bass - I could understand from that perspective. They cannot control a large speaker that well.

I do agree that they are about the only solid state amp out there that sounds as smooth as a tube amp (an ultra pure one). A tube amp still has a little more magic and life to it.

All the above is mean't in good tone. Don't mean to be ornery, just my opinion.