McIntosh C47 preamp question: My preamp has two outputs which I currently have setup with two separate amplifiers. The amplifiers power two sets of speakers in the same room. My dilemma is that one set of speakers are more efficient than the second set, 92db vs 88 db. I was wondering if there is a way I can limit the output to the higher efficiency speakers to get them to balance out better? I read over the owners manual but there is nothing indicating that the two outputs can be "trimmed", but hopefully i'm missing something. Thanks!