balanced vs unbalanced output

Bob - you said it right. It is a kind of insurance against noise and there is no reason they should sound worse (other than shield unfortunately grounded on both ends). My Rowland class D amp doesn't even have unbalanced input - very mature on Jeff Rowland side in presence of class D introduced electrical noise.

Dreadhead - I'm not sure why you're bringing Rocky into this.

Mlsstl - when I mentioned no technical reasons I was thinking of cable alone. You are right - there are some shortcomings of balanced like distortions caused by transformer at lower frequencies or additional component (instrumentation amp) in the chain. Balanced can be grounded at the input, of course, but it defies the purpose of the balanced cable.