I don't know about loosing quality but it will pick up noise if it is unbalenced.

With good cables you can run a balanced signal about 200 meters with no noticable loss. Beyond that the highs and transients will start to go.

Digital signals, however, tend to be much more sensitive, though once again, good cables will go a long way.

Search for information about electrical resistance, capacitance and inductance for more information.

Unbalanced you want to keep as short as possible. Definitely six meters would be about the max.