I am using balanced inputs and outputs with an Audio Logic 24MXL. As my Levinson 39 transport works best with a balanced output and my Levinson 380 preamp works best with balanced input (and output) I never have done a direct comparison of balanced versus unbalanced with the exact same cables to determine if a difference was distinctive with the AL 24.
I can tell you this. The AL24MXL put the DAC output of the Levinson 39 to shame and that was why I bought it. The only time I have heard my AL24MXL with unbalanced outputs was when I took it to a friends house to A-B it to a Theta Gen VIII DAC. I think the Theta had an XLR output and the Audio Logic had (out of necessity based on available cables and inputs) a balanced output. The Theta smoked it - particularly in the articulation and tightness of the bass.
However, I would still want to run that same test in my own system, with all balanced cables, before I will flat out concede superiority to the Gen VIII. But at twice the price, it SHOULD be better! But once I get a chance to make that comparison, the Gen VIII may be next in the ongoing upgrade path. That or the dCS Elgar.
Generally speaking though, I don't know one instance of balanced cables HURTING the sound quality (all things being equal), but because of the internal design of some electroncis, I have heard unbalanced operation that was clearly inferior.
I hope this helps.
