Well I found a pdf of the owners manual online and it says to attach only speakers with an 8ohm load or higher to prevent damage, so I guess this answers my question. I don't see the point in making a stereo only receiver these days if it isn't going to handle 4ohms.
As for Sherwood being the same as Denon, I don't know. This particular receiver doesn't seem to correspond with anything Denon offers.