New amp recommendations

Check out the review in The Absolute Sound for the Musical Fidelity M6CD/M6PRE/M6PRX. You might want to consider the M6PRX, which is a seriously fine amplifier ($3500 list new). In the TAS review, the author specifically mentions Proac as a good pairing. There's a used M6PRX for sale on Audiogon right now (the first one I've seen come up) for $2100 which is a terrific value. I have no connection with the seller, but I do own an M6PRX so I know what a great amp it is.

I think ProAc uses Audio Research in speaker development/voicing. That should be a place to start.

I can't recommend anything because I have no idea what your budget, room size, preferences, etc. are. Just threw out the ARC recommendation due to ProAc's use of them.

Some additional background and input: the size of the listening room is approx. 450 sq. feet, music that I listen to is pretty much everything other than metal and rap, budget: max 5k. Thanks!

I think a Parasound A21 will work great for you. It will save you $$$ for more music and other accessories.

just to be contrarian, (unless of course you want to sell it to me) i'd be really reluctant to replace your integra amp--it's a fantastic sounding piece which would cost something like $8k in today's bucks. to be honest, i've only heard it paired with pre-amps of similar vintage (like the integra 308), and i haven't heard it with your (excellent) proacs so i can't recommend a specific modern preamp, but at your budget you can afford to experiment a bit (tubes? passive?). kbarkamian's idea for ARC makes some sense.