As always, bless you Mr. Russell.
JohnK's got a point - suddenly at 50ft, 1 inch... you're not going to suddenly be disappointed with your 16ga in-wall.
All literature is going to tell you something different, Crown amps
, for instance, suggest that a damping factor of 500 is good for home hi-fi (and you can get away with 75 in live event audio)... your setup (consulting their nomograph) gives a damping factor of 20, which they'd suggest is good enough for panhandlers and micing the Farmer Says
. Not surprisingly, they tried to sell us an IQ System along with our Com-Tech 1600 & 800 amps to help make this dream a reality, so take that all with a grain of salt.
Oh, and consulting the nomograph, they'd have you using AWG#2 wire at 50 feet.