Upgrade the speakers or upgrade the receiver?

The Paradigm Studio 60s are much more capable than you know. I had a Pioneer Elite 49tx driving my 60s V.1 and for the same money on separate amp and preamp, the difference was night and day. The receiver does offer good value driving your surrounds and performing processing capabilities though. I think the preamp section of a typical HT receiver is worst than the amp section of a receiver, so as long as you have the receiver in the signal chain, your speakers are still hampered sonically.

You're not going to be happy with the Paradigm 100's if you try to drive them with a receiver.

I'd say you are wrong on both fronts. Ditch the receiver idea and go with quality separates. And later on ditch the Paradigm idea and go with quality speakers.

Oz