adcom vs parasound dilema

I would choose neither. I would look for an Odyssey Audio or Muse 100 or maybe Bryston and get a smoother, cleaner, and tighter bass response with less etching or hardness on the top end than either the Adcom or Parasound. If you have a friend that has any of their products check them out. I'm sure you will like them.

I had a pair of Magnepan 3.3Rs.
I tried them with (2) Adcom 555IIs,
and (2) Parasound HCA1200As.
The Parasounds were a newer design, and sounded less forward than the Adcoms.
This was confirmed when I tried the same amps on my Counterpoint Clearfield Monitors. This speaker had the same aluninum Vifa tweeter as the early 3 series Thiels,
(before they went to the propietary concentric tweeter/midrange).
The Adcoms were just plain unpleasant on the Vifa tweeter.

The HCA-1500a is a nice amp for the money. It's significantly better than the HCA-1201 and the Adcoms you mention. To my ears, in my system, it compared favorably with a McCormack DNA-1. It has great control over the bass and isn't as harsh on the top end as some SS amps I've heard. However, there are smoother SS amps I would consider first like Odyssey Stratos or Belles 150A