Major upgrade to the audio system

[Bill E]

I've reworked the enhanced audio code, spent time determining tuning params, added documentation. If I do say so myself, playing via Peter Samson's music program sounds great now with the parameters as set. You can change parameters on the fly if you want to experiment.

I added a hidden switch to my -1 so I can connect the audio to an external amp and speakers, as they do at CHM. I didn't use a Heathkit amp, though. :)

The Little Fugue played thru my (original, back when Klipsch made real speakers) Klipsch speakers really sounds impressive.

I also upgraded the super-cheap audio dongle with a slightly less cheap higher performance dongle. Does it make a difference? Don't know, but it was $10.

I've also noticed a fair amount of low-level noise even when nothing is being played, I suspect poor power supply filtering. I'm using a pi5.

Bill