I'd had several Adcom amps and all had worked flawlessly so when I needed additional channels the GFA-7500 fit my needs nicely. I bought it used a couple of years ago and it's been flawless. Unlike some earlier Adcom amps, it has a 12V trigger. Like most Adcoms it does not have individual channel gain control which is fine with me because gain controls tend to get flaky and noisy and eventually need to be bypassed or replaced.
Recommend this product?
Right now I'm using the 7500 to drive four 15" subwoofers. It has high damping and lots of headroom (into 4 ohms) so is great for this task. The 225 Watts per channel perfectly matches the Xmax of my subs and the headroom matches their Xmech.
This amp also draws only about 80VA (about 50 Watts) at idle so runs cooler than most bipolar amps and much cooler than FET amps. It isn't "musical" like an FET amp, but I prefer accuracy over "musical" so that the music can do it's own thing without help from distortion from an amplifier (even if that distortion does provide a "warm" or "musical" sound).
You won't see these every day on ebay, but they do command $400 to $600 as they should given the value they offer.
Amount Paid (US$): 500