I corresponded with TDSS who service NuPrime about this issue and this is what I was told
"The fact is, even though it is perceived that Balanced cables are in some way superior to unbalanced, depending on the performance objective that is NOT a universally true concept. In pro sound or anywhere you must use a long run of line-level cable, then Balanced usually has the edge as a result of its superior low noise performance. But... the noise in question is not "self-noise," but noise contamination from the external environment (radio frequency contamination or 60Hz AC power noise from nearby wires, etc.). In such cases Balanced lines are almost always superior when it comes to the final sound.
Conversely, if protection from externally sourced noise contamination is not a need or concern, then believe it or not Unbalanced is usually better. Think about it... name me any two objects or set of conditions anywhere in the universe that are perfectly identical in every way down to the sub-atomic dimensions? You can't because there is no such thing - there are no two objects that are identical anywhere in the universe.
OK, the Input and Output stages of the Balanced signal transfer concept relies on the fact that both the Non-Inverting and Inverting signal lines be IDENTICAL to the nth degree for ultimate performance. Well, as I pointed out there is no such thing. Uh, ohh... what happens if they are not?
Well, the closer the better for sure, but there is a limit to the amount of "identical-ness" that can be achieved, and that limit is about 90db with respect to dynamic range. OK, and our NuPrime gear has specified dynamic range of at least 110dB (ST-10). Furthermore, when it comes to Balanced operation the primary specification is called the Common Mode Rejection Ratio (CMRR). NuPrime doesn't even list that spec so we have no assurance that the CMRR will match the 110dB dynamic range - and based on most instances of CMRR, 90dB is about as good as it gets.
So, going Balanced we are potentially "throwing away" 10dB of dynamic range. That means there will be unwanted low-level signals that are "filling in" where that 10dB of silence would otherwise reside. Then there is the makeup of those unwanted signals - what are they? They will be signals from the opposite phase line that are not canceled by those of the other phase. That means signals of various frequency from the music that are artificially being being amplified as a result of the insufficient CMRR. They can either be in-phase or out of phase with respect to the primary signal that we want. If they are in phase, certain tones and harmonics will be excessively boosted. If out of phase the perceived harmonic balance will be shifted. Either way, we loose resolution and accuracy with respect to the original signal.
In light of the above we would prefer NOT to use Balanced lines unless the contamination from external noise signals requires it. In virtually all but the worst possible cases (like living next door to a radio station), a 1-meter pair of unbalanced cables will never intercept enough external noise to make going Balanced remotely advantageous."
