sorry i cannot comment on the 4ohm test (i am using the y2600 as a prepro to my ATI2007), but most of the better quality receivers in the 1k price range can drive 4 ohms.

audioholics tested the older rxv2500 and found it did fine driving the RBH1266se which are 4ohm speakers. their final review on the RXV2600 isn't done yet.