I'm glad I could help bfp. Not so long ago I was the one asking questions. What you can and can't hear is not that strait forward. If it is a very short spike over a narrow freqency range, you are much less likely to hear it than if it is a spike or dip over a wider range, say from 100-200 hz (from what I have read anyway). Some people claim to be able to hear differences of 1db. For whatever reason, the industry has taken to quoting the +-3db range.
I expect any Denon would be able to handle 4ohms. For some reason, some companys who's receivers are known to handle 4ohm loads say they don't. Denon, Harmon Karden, Sherwood Newcastle, Maranz; these are all receivers that should handle 4ohms just fine. Yamaha is hit and miss. Some models are fine, some are not.
