I have heard significant differences between balanced and unbalanced ICs in my own system, and decided that I did not like balanced-- too dry (thin, lean?), too detailed, too analytical. Single ended sounds more "whole", more organic, warmer, more rounded, more coherent, and more natural to me.
Both Steve McCormack of SMc, and Sonic Frontiers recommend balanced (my amp and pre-amp) ICs, but I don't like it and I plan on staying with high quality single ended ICs. A Rep. at Synergistic Research feels tha same way I do and prefers single-ended for the reasons I've stated, but he also admitted that most of his colleagues probably preferred balanced. It really comes down to personal preference IMO. Cheers. Craig.