Test it out by using the back surround channels of the 7700 to see if you hear a difference. The 886 manual has pretty clear instructions on how to Bi-amp your speakers and you have to set a menu item for your speakers to Bi-Amp to make it work internally. With the efficiency of the Klipsch system another 200 watts just for the horns may need some tweaking. I don't know if connecting the XLR connections disables the RCA outputs through some mechanical wizardry or not.
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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