RW,
I have been fan for Adcom products for number of years although I haven't bought their product for a while now. I have used GFA 6000(I still have the amp), GFA 5300(sold it), GFA 5800(currently powering my R/L front pairs), and tried GFA 5802 to compare to GFA 5800 but decided to keep the GFA 5800. My experience with Adcom amps were generally favorable over the years compare to other amps. My current GFA 5800 has been my favorite for a long time, if GFA 7500 amp gives you no problem, I would definitely keep that amp for little longer. Outlaw 7125 amp is no doubt excellent product but I doubt if it will significantly outperform your GFA 7500. I don't have any current experience with Adcom digital pre/pro hence my last Adcom pre/pro was GTP 600 analog preamp but I still use GDA 600 and GCD 700 in my two channel only system.