THE familiar, integrated, thumping Bose sound system has become an Audi trademark - and the 170-Watt audio in the RS4 is every bit as good as we've come to expect. The system features a six-stack CD changer located in a recess behind the cargo trim, six speakers (one large speaker in each door plus a high-mounted tweeter near the front doorhandles), auto-reverse cassette and a security coded, electronic tune AM/FM radio. The aerial is fixed to the roof and cannot be adjusted for height. There are no steering wheel-mounted controls and the on/off volume knob is at the furthermost position from the driver.