Arcam SA20 vs. Parasound P6

The P7 is a really great preamp if you aren't buying the JC discrete models. The P5 and 6... meh.

I would use the Adcom as your preamp 1st prior to purchasing a new preamp. Learn to appreciate the improvements the separate amp is providing. 

Then consider replacing the Adcom with a preamp. Possibly consider getting a separate DAC at that time.  Keep digital circuits away from analog ones.

You might consider a tube preamp. They generally provide the smooth mid/treble and soundstage you are interested in. 

Thanks for the advice. The P7 is even more wasted function when you're running a 2.0 system! 

I may go ahead and plan on a separate DAC, like you suggested. I was hoping to find a one box solution. 

I originally ran my Arcam AV40 as my full feature pre-amp, streamer and DAC. Even adding a relatively inexpensive Bluesound Node provided improvement a notable improvement in sound despite it running into the Arcam as a streaming source. The amp at that time was the Arcam PA240.

You could use the Arcam as your source/streamer and send it into a dedicated pre-amp. Arcam is great for what it is, but it's designed to have a multitude of capabilities at the expense of being special at any one thing.