Proceed AMP-2 vs BPA-2 / HPA-2

What are the sonic differences between the AMP series and the BPA/HPA series? I've read the AMP series can be a little dryer, but I read that quoting someone who was quoting someone so it's 4th hand information. Does anyone have any real world comparison experience?

I recently acquired a Proceed PAV for a new budget dedicated 2 channel reference (for me) system I am putting together.

In the next couple of months I am going to add a new amplifier. This new amp will drive NHT 2.5i's. I guess you could say I am putting together a mid 90s vintage system. I fell in love with Proceed gear looking at ads and reviews back in HS and College but it was obviously out of my league. I was reading recently about how the old Proceed HT gear is a great bargain for 2 channel listening as well. A PAV popped up in a local craigslist ad and I pounced on it. A few days later the NHT speakers came up (an extremely rare case of WAF with regards to towers).

I am coming from an Arcam A80 integrated which will remain with my HT/2 channel set up. Eventually, once I've transitioned everything, the sources will be: rega p2/goldring 1042/grado ph-1 and an appleTV with either a Cambridge DACMagic or a Bel Canto DAC 1.5.

All that being said, I really want to stay in the Proceed family (unfortunately as an architect, aesthetics are a major deal to me) to match my PAV. Also I'd like to stay within the $500-$600 budget which seems like is the price range for an AMP2 or BPA2. However, I've read great things about the HPA2.

My basic questions are: 1)which is the best amp for my system? What are the sonic differences between the AMP series and the BPA/HPA series?

I suppose if I went outside the Proceed family, I would be interested in MAC amps or Bel Canto, but that is neither here nor there.

Thanks for any advice.