Thanks again, few questions about your code.

How do you cope with channel assignment ?
Do you simply clone AY channels to SCC+AY or you have some kind of static assignments (e.g. if SCC is present use SCC for music and PSG for FX)?

OK, but what about the way it works?
I mean, how do you manage the channels ?

I understand that pt3 has 3 tracks only, FX have 1 track only,
while
PSG has 3 channels and SCC has 5 channels.

How do you map tracks on channels when scc is present ?
How do you map tracks on channels when there is psg only ?

Do you select the track that has each time has the loudest volume ?
Do you use some kind of priorities ?

Do you do some kind of "cloning" when the number of channels exceed the number of tracks (in order to enrich the sound) ?

(When SCC is present you have 3+1=4 tracks against 5+3=8 channels, so in theory you could adopt a static assignment 1:2, what do you do actually ?)

AFAI understand Shiru's player should have some sort of priorities,
based on the time you have been playing a sound and on the relative volumes.
(e.g. : play the 3 loudest channels at each time out of 4 tracks, or
play : always the newest sound and skip the oldest).