What is the best method of connecting my N72 and J99 preamps to an unbalanced input? Do a need to make an adapter cable or can I simply connect an XLR to TRS into a 1/4" unbalanced input?
It depends on the input jack. If it's really a TRS jack and not just TS, it must connect R to S. If it doesn't you'll need to make or modify the cable so the R to S connection is made.