I could never listen thru a single ended pre-amp. Single ended source hooked to a balanced pre-amp can be ok though, depending on the design. Phono stages, for example- not much choice there. Balanced cd playback often helps free the medium from the "closed in" sound that is it's hallmark. And, certainly the balanced pre-amp should be hooked to a balanced amp. Even if that amp is not true differential. Balanced (differential) pre-amps IME, allow the system to achieve superior: Soundstage, defined images, tighter more accurate bass, lower noise floor, wider dynamic range. All without loosing musicality, if done right.