With a amp that powerful, you will be safe with any of these choices. I've actually heard all three, and they all sounded very good. My personal preference would be the Soliloquy 6.3, but mostly because they are a much easier load to drive with a tube amp. Using a SS amp, they didn't sound as good as my friend's pair of Dynaudio S3.4's being driven by a Krell amp. I'd have to say that I preffered the Danes over the AA 7B. The 7B's are still very fine speakers, my tastes lean towards the warm side of neutral, and the Danes had that richer midband, IMHO. Not quite as rich as a Cary V-12i tube amp driving the 6.3's, but very nice nonetheless. The AA 7B's image well and are more dynamic, they are an excellent choice as well. All three speakers will work well when matched with the right components. Your musical tastes could favor one over the other. If you are set on that amp, my first choice would be the S3.4's, followed by the 7B's and then the 6.3's. If you value dynamics over warmth you may prefer the 7B's. BTW, I heard the 7B's driven by a Classe CA-300, which seemed to control them very nicely.
Good luck and happy listening,
John
Good luck and happy listening,
John