Simple (for me, anyway) test: tap your speaker through pad and send to converter. The only difference in wire gauge at AF is resistance. The resistance must get high enough to be material with respect to the varying impedance of the driver in question to be audible. You can solve for that, or you can just measure the change in frequency response as you change cable gauge with the test rig formerly described.
I am not that bored, so I'm not going to do it myself . . .
It's not from the speaker wires. You'd have to tell more about your setup to get a good answer on that. It could be your pre amp, your gain staging, your mic or instrument, your computer's processor and/or software etc... It could even be a bad speaker coil or amp. Are they new? Did you ever hear them work right? Swapping out parts one at a time is a good way to narrow down the problem.e.g try a different speaker, amp, mic etc... You have to love trouble shooting!
Been there, done that. Long time ago, before the best part of your punk-ass dribbled down you daddy's leg. One step up in gauge will not make a noticeable difference in sound quality in anything other than a sealed chamber- and then, only your DOG will be able to hear it. I will go along with Lt. Bob's and SSGlen's statement that a step up from 18-ga. (very thin) to 12-ga. (substantial) can make a difference, and going from instrument cable (very, very thin) to speaker illustrates the difference, but 18 to 16? You are only fooling yourself.
I got something to stick in your mouth right here...
Actually...I was the one who first mentioned about going from 18 to 12, not Bob or Glenn...and I never specifically brought up going 18 to 16, other than to say it would be a waste and you might as well go for something heavier if you are going to even bother.
What I also said was that going from light gauge to heavy gauge makes a difference, and most will agree.
I mean...if you can't hear it...that doesn't invalidate the fact that others can.
But if you wanna split hairs about 18/16...then pull one off your ass and split it...or just keep playing with whatever it is that you "got right there".....