@imhififan I haven’t listened with headphones. If I listen with headphones and it comes through in both channels vs. still has no output via left. What would that tell me?If listen with headphones and it comes through in both channels, the preamp section is fine.
If listen with headphones and still has no output via left, could be problem from the preamp section or the source.
Another way to verify is connect a source with volume control or another preamp via HT bypass (bypass the preamp section).