Hello.
There has been a few times where audio seems very distorted or driven too hard on the TC64's audio out. The game Time Tunnel is pretty basic in its musics, but those all sound wayyy too distorted as if the audio levels get driven too hard. See a youtube video of Time Tunnel for the C64, then try it on the TC64's audio out. There is a demo that does the same thing. The audio sounds distorted, though it at least seems to play it right.
Just wanted to see if there is something I am overlooking in the SID options. Audio output level of the original SID is definitely much higher than the audio output level of the TC64.