trikos,my 1050 has a switch on the back for 4 or 8 ohm speakers

arntz,i was buzzing the manual to see if possibly the denon had such a switch,but no.
i'll jump on the bandwagon and agree you have a load problem and i noticed that the 8 ohm rating was full range 100w/.05%thd but at 6 ohm 135w/1khz .7%thd.so obviously the amp is struggling as the load drops.if i was able to afford amps for at least all 3 fronts,i wouldn't just amp the center