Just checked on my 8500 - shouldn't be all that much different?
Playing a CD from cold, the tape motor stays off. If I switch to tape the motor starts (no surprise there!) but if I switch back to CD then the tape motor stays running. No idea if it times out and switches itself off. The tape motor isn't noisy, just a very faint rustle if I listen up close with the lid open.
Cheers, Steve