well....
as an option you can crank the speakers up pretty loud and adjust the volume through windows.
You may want to wait before drilling the hole - to see how often sound adjustment is necessary.
And, the volume is a dial on the cord (with plenty of extra cord). You could replace the dial with a pots based volume from radio shack or something. Have a knob sticking out somewhere. I suggest you just tuck it all inside and wait and see.