Originally Posted by McStyvie
I just use the denon x4000 to run them, and before that just the 2309. It is enough to run them fine, it will take them all to reference without breaking a sweat.
If you go for an amp, go for less distortion than the Denon, not raw Watts, because you will probably never even come close to using all the watts available per channel even with just the Denon.
With 683s I would definitely go with the 685s for surrounds. They match really well with them. Even as a center they are very well suited.
as for the Pioneer, I would never consider it because it does not EQ bass (anything below 63 hz I believe). Though the new ones coming out this year will apparently.
But that was a must for me when searching for a receiver, using dual subs, and planning to go to four at some point.
I also use REW and a Mini DSP for that for what it is worth.
Some will tell you it does not matter that the subs will not be EQ'd, but it does to me and to many others.
I have played with a few different amps to power my 683's, and like different things about each.
Pioneer SC-65 onboard class D amps - VERY nice imaging, a bit on the warm side, with a slightly bright top end when pushed. Bass is tricky and unrefined.
Emotiva XPA-3 - GOBS of power, bottom end is very well controlled and sublime, but top end is hissy.
Marantz MA-700 mono blocks - Well controlled, very musical mid-bass region, high-mids can get squelchy. (If anyone else has experience in the pro-audio world, these amps sound "British")
Peachtree 220 - SWEET highs! Really really nice top end, strange sense of space (mids are almost too far back behind the soundstage), bottom end is almost clippy, like it isn't really pushing the 220wpc it is spec'd for.
Overall, I think the best amp for the 683 has been, shockingly, the onboard Pioneer amps. They do run out of stink trying to control the bottom end of the 683, but other than that, don't have any glaring character faults, and in fact sound REALLY nice at low volumes. Second favorite would be the Peachtree, but I ran into some QC trouble with that unit. The Emotiva is a close third because the bottom was amazing...so much so that I'm considering giving an XPA-2 a listen. The Marantz, first of all is built like a tank, but just made vocals sound too harsh, and as such was my least favorite amp.
One important thing that I have taken away from all of this is that the 683 really does like a LOT of power, and the more I've given it, the better the bottom sounded.