Could someone tell me what, if any, difference in sound there would be if I took a head that had 16 and 4 ohm outs and used the same cab+speakers, one time wired for 16 ohm, the other time wired 4 ohm?
Some people believe that there's a difference in sound (maybe in matters of clarity)...

But actually, I think you won't hear any difference...

Take a look at my profile!
not a good idea to be messing with the values, espesialy with tube amps. can be fatal.
just use the right output and the right input, dont mess around.
Quote by Scowmoo

You deserved this, Matt.
I guess I didn't say that I would use the 16 out for the cab when wired for 16 and 4 for 4.
Specificity is my friend, but we don't see each other too often. :/
you wont notice much of a difference, but the sound is a little ..i dunno how to describe it.. fuller or like.. beefier when you use the 16 ohm out

I think the reasoning behind that, is that you're using all the winds of the output transformer's secondary with 16 ohms, and using much less when hooked up to the 4 ohm tap