I can barely hear output even when the volume is at... (by 2 users)

I got a system from a friend of mine that appears to be in great shape however, when I hooked it up I can barely hear the sound out of the speakers. I tested the speakers with another system and they were fine. If I crank the volume up to 'full blast' I can hear it but faintly. Its like standing next to someone who has ear buds in and the volume is too high, you can hear the tinny overflow but its not really music.

I looked for something that would look like a fuse or switch on the outside of the case but nothing. I pressed the help/reset button and the text says system is operating correctly.

Any advice is appreciated. I have it connected to a tuner and a cd player and the result is the same regardless of the source.

Thanks in advance.

System: Technics SU-G88