Adcom Preamps 565 & 710- Any difference?


I am looking to consolidate all the separate small boxes (i.e., a NAD phono stage, a generic switch box, etc) into one unit. I have a low end Adcom (GFP-350) and an Adcom 5200 amp and want to upgrade the preamp. I keep seeing the 565 (an early 1990's vintage unit, I presume) and the 710 (a later 1990's preamp, also an assumption) on eBay and this site and am interested. What exactly is the difference- in price, in quality, in features? Why does the 565 generally sell for more? Any other preamp in the modest range I should be looking at?
ncallander
The GFP-710 is a current Adcom product. It came out a few years ago and is very similar (feature wise) to the 565. It also has a remote control. The Absolute Sound (Neil Gader)did a review on this piece last year
How does the Adcom GFP-565 compare sonically with the top-of-the-line Adcom GFP-750 preamp?
After living with the 565 for almost a year, I can say it is a top notch piece of equipment. I heartily recommend it. My Adcom GFA 5200, however, hums and is underpowered for my multi-speaker listening. I am looking for something more powerful. NMC