balanced lines offer less coloration even if they are only 6" long
6" This is false, your either hearing things or your biased toward your own retail preamp product.
In many cd players or dacs I've seen the balanced output is just an added opamp changing the "real' single ended circuit to balanced. Same goes with the input of many poweramps, which btw are single ended output to the speakers.
The only time balanced is better from source to to pre, or pre to power is for noise cancellation with interconnect over 5mts>
Cheers George