Question re: "balanced" audio setup

I'm a little confused what a "balanced" system means exactly.

I'm interested in the new Musical Fidelity Tri-vista 21 DAC, but it's not a balanced unit. It has single-ended outputs. (Musical Fidelity's Anthony Michaelson says in the Jan Stereophile that he doesn't believe in adding balanced outputs to his equipment, as he doesn't think it really makes any difference in the noise level of the system...(?))

Say I have an all-balanced system: a balanced amp, preamp, and CD Transport. Say these are all connected via their balanced outputs and inputs using balanced XLR cabling.

If I connect the non-balanced DAC to the balanced CD transport (and thus to the balanced preamp and amp), does that screw up the whole "balanced" system? Do I "unbalance" the whole setup?

The point of creating a "balanced" system is to reduce noise in the system, right?

So if I were to add the unbalanced DAC to the setup, would all the $$$ spent on the balanced components still be worth it?

This may be obvious to some people, but I'm kinda confused.
As you have probably noted from reading the posts here on A-gon, there are differing opinions about the efficacy of balanced connections in most home audio systems. It's true that balanced connections provide lower noise in systems where the interconnects are really long, or there is a lot of electronic interference in the environment. Since most home audio systems utilize interconnects that are no longer than 2 meters, it's questionable if balanced interconnects offer better performance than single-ended interconnects. I have tried both balanced and unbalanced connections in my own system, and I honestly can't hear any audible differences.

In a balanced set of connections, both the incoming and outgoing signal are referenced to ground, whereas an unbalanced connection references the signal to the ground plane of the component. Therefore, connecting your unbalanced DAC to the balanced inputs of the CD transport should not have any effect on the rest of the (balanced) system.

The balanced components that are "downstream" of the CD transport and DAC will still retain their potential advantage for noise reduction.

On balance (pun intended), I wouldn't worry about the issue of noise unless you have VERY long interconnects (say, 15 feet or more), or a listening environment that has a LOT of electro-magnetic interference.