This is a debatable subject. Most, if not all, balanced amps/pre use XLR type connections. Balanced connections helps reduce feedback such as when connecting microphones to the amp and also allow long cable runs while reducing RF interference. If your amp doesnt have XLR inputs then I would stick with the unbalanced version of the preprocessor. IMO that the unbalanced version is $1000.00 less than the balanced one. Here is a link that briefly explains what balanced connections do:

http://homerecording.miningco.com/li...y/aa082697.htm