@keithjacksontucson If you have a balanced amplifier then a balanced preamp will help you get the lowest distortion out of your amp(s).
But most high end audio preamps do not support the balanced standard! The standard is important in that it helps prevent ground loops and helps prevent the interconnect cables from having a sonic fingerprint- if you've ever had to audition cables to see which sounds better, you know what I mean. Here's the balanced standard in a nutshell:
1) pin 1 is ground, pins 2 and 3 carry the signal; in the US pin 2 is the non-inverted side of the signal.
2) ground is **ignored**. In this way the shield does not play a role in the sound of the cable. Put another way, the signal is not referenced to ground so there is no circuit completion done by the shield as there is with a single-ended cable.
3) the output impedance of the source (preamp in this case) can drive a low impedance (1000 ohms is typical).
To this end, nearly every cartridge made these days is a balanced source and most tonearms can be operated as a balanced source as a result, simply by use of the correct interconnect cable.
Traditionally the only way to drive a balanced line and support the standard (also known as AES48) was with an output transformer. Balanced and single-ended are inherently incompatible (there is no such thing as 'quasi-balanced' or any such nonsense); for this reason if you see a preamp that has balanced outputs and also RCA outputs and there isn't a switch to go from one to the other, then you can conclude that the preamp does not support the standard. This is because an RCA connection employs ground; if there is no switch that means that the XLR output does too. The good news is it is possible to properly drive a balanced line without using an output transformer and it can be done with tubes.
