JVC RX-618V SOUND IS MUFFLED

check to see if the radio is clear. If it is it may be the signal going into the amplifier. if it is muffled as well, depending if you have an Equalizer hooked to the unit. This also could cause the problem. Finally check the bass, treble balance and volume knob but turn them back and forth while unit is on and see if signal clears up momentarily. if this is the case the control knobs need to be cleaned. Also spin the connection jacks {RCAs} in the rear and see if this clears it up. If not you may have to have the unit serviced by a professional.