24GA is pretty small for driving a speaker. While it will work you might try doubling up the wires, 2 for the + and 2 for the -, this will give you ~21GA. If you have enough and can get three or four pieces in the hole even even better. There isn't much resistance in 3" of wire but no sense in restricting current flow if you can avoid it.
Twisting the + and - together will make the a little less sensitive to radiated noise, which there is plenty of with and Class D amp, I'd twist them myself.
mike