I do agree that the connection physically and the distance can be a contributing factor,however many of the designs I have heard with strictly balanced out to amp sounded worse than using the single ended,so I suppose many of these factors are part of the circutry. Also I have heard balanced all the way through from cd to amp and they sound night and day better. For example I listened to a krell(not my favorite)intergrated amp,I think the 300i or something and with this design they installed a switch so you can change between the single ended input and the balanced from the same cd player outputting both cables into the amp at the same time, so you could do a perfect AB test, and the balanced in just was killer compared to the single ended,but I did not have this experiance by just hearing the amp ran balanced after any pre-amp without the source going in balanced..So I dont know,besides the superior connection of balanced and the possibility of running 50ft with less signal degrading I dont see or hear any reason to run only balanced out of pre...
