Yes, the Q switch turns the multi-prong socket in the back on and off, I'm told. (I have one, but it is among the many works in progress.) Apparently the act of plugging a signal-source device into that socket is enough to disconnect the input from the regular source (antenna) and replace it with the tape player or ipod on the other end of that adapter cord that's posted about here occasionally. Then when the connection is broken by disconnecting said device, input is automatically switched back to the antenna again and, a viola, she is again ze simple radio. The feature that the Q button adds is the simple switching on and off of that entire circuit, thus eliminating the tiresome necessity of actually unplugging ones ipod to return to radio reception/plugging back in again for recorded tunes. So, it's an on/off switch for remote inputs. Slick, no? (Apparently it's a fairly rare feature, as is the radio model, I think; wish it were stereo.)
Happy audio enjoyment,
Denny