Unless you are going to have long cable runs between the AVR and the amp the XLR connectors will not provide a higher quality connection except that the XLR connections are mechanically stronger. You can't go wrong with any of the amps as far as I am concerned. I bought my 7500 because it was on sale at the time. I also have a 7125 in case I need more channels but my 5.1 setup is perfect for me.
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Music system
Model 990/7500/Magnepan 1.6 QRs/Technics SL1200 MK2/Aperion S-12 Subwoofer/OWA3/Sony NS75H DVD
APC H15 Power Conditioner

TV System
Large Advent Loudspeakers/ Polk center/Monoprice surrounds/Panasonic Viera 42 inch/Onkyo HT-RC260/Sony BDP S590/Directv


Home Theater System
Onkyo PR-SC886/Outlaw 7125 Klipsch RF-82 L/R,RC-62 center, RB-35 SR/SL, BENQ HT1075, Outlaw LFM1-EX/OPPO BDP-83/Directv
Harmony ONE
Blue Jeans and Monoprice interconnects
APC H15 Power Conditioner