Aragon, Parasound or Bryston

The older Aragon amplifiers are very nice -- they have a lot of current but they are a little on the warm/slow side.  Still have a lot of energy to the music.  I have heard the first gen Bryston amps (like 4B).  They are okay, but are a little flat sounding.  The newer generations (SST / SST2) are much better and more exciting.  I would probably pick the Aragon over the Bryston because the Aragon will just pull you into the music more.  That being said, I would probably choose the Paraouns A21 from your short list because it's the newest platform and the Parasound has some excellent feedback.  You won't have to worry about aging capacitors and components that need to be refreshed (the Aragon/Bryston are quite old).

Tubes ahead of the Bryston might be pleasant, they are forward sounding at times, I preferred mine on bass management which btw does well with. Having some experience with Parasound and Paradigm, they are a nice combination. Have not entered tubes into the equation but I dont think you could go wrong with the VTL in front of the halo.   

Easy.  Parasound.

I would get the A21. I've heard it with your preamp and its a very good match. The 4B would be my 2nd choice.

Parasound is the most accurate,musical with great body and weight.Your move!!