The game sound itself or sound from notes/chords you play on your guitar? If sound from your guitar, you can try setting your Real Tone Cable Gain again, except when doing so, turn your volume knob on guitar to around halfway. Do the strums to pass the soundcheck. Once complete, turn your volume knob back up. I recently had some issues before replacing my strings, had to set my tone gain to 1.0 db and do this process to get my lower B, E strings to pickup properly. Of course, they were just worn badly and needed a new set but it got me playing until I chucked the old ones. Game itself, you can delete the Rocksmith.ini which will be recreated when you start the game up which will reset the games settings to default. (you can reset options from within the game too, but if that doesn't work, try deleting the file to force it back to default incase maybe it isn't resetting) You can backup your DLC folder from the game, uninstall/reinstall Rockmith then moved the DLC folder back overwriting the newly installed game which will put your music back without losing them. There are several guides as well via google that go through setting the Real Tone USB recording levels within your OS as well as some audio settings.