As it has been said, no you can't add another channel to the PM 4.1. Are there powered single channel speakers for not too much $$? I got the 4.1 refurbs, and recently picked up the 5.1 DD Decoder. He has 5.1 channel output, as do I. There are powered studio monitors out there that might do the trick, has anyone tried it? I have noticed that without the center channel, dialog can get drowned out by everything else. Has anyone had experience with a self powered single channel speaker?