It also doesn't necessarily mean a balanced connection or a fully balanced design circuit (i.e MP-3) will give you lower noise or have any advantage over single ended design. Fully balance design circuit will also susceptible to hum problems too.Just a correction here, since this statement is essentially false.
The advantage that balanced operation has is several- immunity to interconnect cables, and the system was also devised to prevent ground loop hum and it works quite well! "Fully balanced design circuit" (sic) is far less susceptible to hum problems- it is better able to reject noise in the power supply and far more able to reject hum from close by power transformers and the like. It is also possible to get lower noise, since if the balanced design is also differential, careful use of well-designed constant current sources will reduce noise while also increasing gain and reducing distortion.
The first bit: immunity to interconnect cables, is likely the most important aspect, since audiophiles are well-known to pay serious money for interconnect cables in search of the cable to rule them all. In effect, cables are the 'hidden cost' of operating single-ended preamps.