Last night, I got kinda curious as to how one might do this without buying a switchbox or whatnot. Noting that my larger amp -- a Yorkville 100B -- has a line out, and I had two patch cords, I plugged my bass into the Yorkville and then put one end of the patch into the line out and then the other end into the input on my Peavey Microbass. Now, it worked in that both amps made sound, but the sound from my Peavey was CRAAAAAZY noisy. Is there a cheap way to do this, but without the crazy, crazy noise? Is this just a problem with poor cables? (these aren't exactly monster cables, ya know).