balanced vs. unbalanced sound quality

I do however have a stronger and tighter bass, actually the whole sound is now very uncolored, I have been told if I go to a pre that has balanced out to the amps balanced I will get some of my volume back because the adapters mute the signal in some way?

The reason this is happening is because the Rotel employs two sets of inputs that are independent of each other. The balanced input converts its output to single-ended; that signal is then applied to the single-ended input.
The balanced input needs two inputs- non-inverted and inverted; if it only gets one (which is what happens when you use an adapter) then the gain is reduced by 6db which is pretty audible.

A balanced preamp would solve this.

I'm guessing Johnson was referring to the signal path length within a balanced circuit, not within a balanced cable.

Often the signal path within a balanced circuit is simpler. At least that is the case in our stuff. For example, in our preamps there are only 2 stages of gain in the phono section and only 1 in the line stage. From LOMC to the ability to drive headphones. Rather than repeat myself though, here's an article that might be helpful regarding balanced operation:http://www.atma-sphere.com/Resources/balanced.php

Professor Keith Johnson has said that the signal travels twice as far in a balanced cable and they present there own set of problems.

That's pretty funny!

If he really said this it suggests he doesn't know what he's talking about!!!
Look at a single ended cable- the signal travels in the center conductor, and the shield is the return path. In a balanced cable, the signal travels in a twisted pair, and the shield is ignored (not used for a return path). The distances are identical.