humm... not sure but i think that Alan's recommendation is 14awg for 25ft or shorter. & 12awg over 25ft.
For my point of view, I run 12awg everywhere possible no matter the lenght ( in my case 35ft is the longer run ).
Is there an hearing difference between 12 & 14 ? not sure, but higher gauge should be TECHNICLY better for bass, (lower resistance & capacitance).
Pricing between 12 & 14 is not a big deal.
16awg i simply don't trust it.
In all case be careful on bargain price from hardware store those a generally poor quality & copper will oxide in mid-term, not easy to splice and not very flexible.
.. and be careful on major Brand Name they are good but generally overpriced.
For my installation most of my wiring is AXIOM 12awg 1$/ft approx. bulk wire & guest what, it's a very flexible wire much more easy to fish than the cheap 14awg from major hardware store at 0.70$/ft
Personnaly i don't like doing wiring and the worst is remake the job in short on mid-term.
A fairly good quality wiring save time,labor & money in long term.
