First and foremost the sound is great. I hadn’t had a HT pre/pro for a while and I’ve been listening to mostly 2 channel and down-mixed movies for past couple of years via a top rated 2 Ch USB DAC (with all the accessories). It didn’t take long to realize the 7704 surpassed the sound quality of my USB DAC setup. The 7704 has a big full “natural” not processed sound. I’m still working out my surround speaker placement and config but the few surround tracks I’ve listen to so far are also quite good. One thing the 7704 has is “options galore” for speaker placement and surround decoders. A good pair of front height speakers really expands the front soundstage once setup properly. I’d recommend setting up front height speakers over surround back speakers if you have to choose between the two. Anyway the 7704 is a definite keeper for me. I expect it’ll be my primary preamp for many years to come. My only gripe so far is with the ridiculously small print on the remote. I can’t see anything on the remote unless it’s in full light. Even the remote backlight is useless once the lights are turned down. There may be slightly better sounding pre/pros out there but I’m sure you’d have to spend MUCH more to get an appreciably better sound than the 7704. It’s a bargain considering the sound quality and features.
BTW, I also purchased an Aircom T9 to help assure the 7704 stays cool and internal components last for many years. The Aircom looks like it was specifically designed for Marantz chassis and at its price point makes the Aircom a no-brainer.