The GFP-750 is hands down the better sonically. The 750 was compared to some of the best. The 565 really wasn't that great overall. I think it achieved a Stereophile Class C or maybe a B rating back when they were sort of honest ratings. The 750 was pretty much universally accepted as a great preamp earning Class A in Stereophile and being received well throughout,
I have owned both, the 750 IS the better pre. The 565 sounds closed in and less dynamic. Its sound is dull in comparison. It takes the vibrancy out of the music.
I have owned both, the 750 IS the better pre. The 565 sounds closed in and less dynamic. Its sound is dull in comparison. It takes the vibrancy out of the music.