XLR balanced cables in general are desighned for the long runs with no noise. Unbalanced though will certainly have greater transparency and details but more hum if you'll go for the long run. I would not advise to use long runs of RCA cables with tube amplifiers on either end.
Go balanced or unblanced that is the question
OK. I think that overall having an extra length of cable between the pre-map and amp is a nice thing.no matter the romm rule of thumb will be i would like to keep the elctronics out of the center.So I have a Mac preamp with XLR outs but whose signal path is not truly balanced.Likewise my Mesa Baron has blanced inputs but it's circut topology is not true balced.But because I have an MIT XLR I use as my single ended stuff is lower cost (quality?I don't know!) wire.Also because of a sub output I need the vaiable main out of my main pre out for my sub.The question is should i be converting the signal back and forth?In Hartley's book he say's that converting back and forth cann screw things up.I have alwasy thought that balanced or unbalanced all the way through was the way to go.I might change to a balned pre but like my amp and want to keep it.But if i need to make a 20 ft. run am i better off risking distortion with an RCA or staying with a reasonabley priced XLR from pre to amp?All my sources of course are RCA.Thoughts?