I'd like to upgrade the speaker wire for my Onkyo 894 HTIB. The back speakers will require 45 feet each. The have a spring clip to feed the wire into. Does anyone know what the largest guage wire that will fit inot that spring clip is?

Just got mine before Christmas and I replaced the supplied supplied speaker wire with simple lamp wire from my local hardware store 16 gauge works fine with the spring clips.

I sent Onkyo the question. They said 14 gauge is the largest wire that will fit in the clip. To hide the wire for my surrounds it will require 41 feet for one speaker and 52 feet for the other.
Can I use 16 gauge wire or would the 14 gauge be the better way to go?

According to this chart, the maximum recommended length for 8 ohm speakers using 16ga wire is 48 feet. So just to play it safe, go with the 14ga. It doesn't cost much more.

http://www.roger-russell.com/wire/wire.htm

the 14ga may have more trouble with the spring clips, but you can always trim some strands at the end, and make the ends thinner.

Wire isnt like a hose, where one narrrow area becomes a chokepoint. You can have a narrow area, and the electrons will flow just fine, within reason.