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.

While you state there are "no 'technical' reasons" against balanced design, I would simply comment again there are some talented designers of well-regarded equipment who apparently are not in full agreement with that statement. They state their case better than I, but at least it makes the point there is not a universal consensus on the subject.

Some designers don't want the added transformer or differential amp needed for balanced. Here's a comment by Robert Harley of Absolute Sound:

The preamplifier's balanced output is then sent from the preamplifier output to the power amplifier's balanced input where it's-that's right-converted to unbalanced with yet another active stage. The result of these unbalanced/balanced/unbalanced/balanced/unbalanced conversions is additional electronics in the signal path-just what we don't want. This is why you can't assume that balanced components sound inherently better than unbalanced ones.

My observation is there are many areas of science and engineering where there is more than one opinion about the best approach to an issue. Building anything involves compromises and choices where different people arrive at different conclusions. Audio is not an exception.

Thanks for an enjoyable discussion.

This is just like watching "Rocky"

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.