ro, can you explain why you need more than 1 channel per sfx, when you play 3-ch music AND sfx'es together? Maybe you like 1-ch music?
I think, 1 channel sfx for PSG is acceptable enough, and it's usual practice for most of games for platforms with simple PSG's (ZX/MSX/SMS/Coleco/NES/etc). Yes, there is no any commands in AYFX editor, because it's more like sample editor in VTII than SEE. ALso, there not a 18 steps (frames actually), there is 1024 steps (try to use cursor keys up/down or mouse wheel); and up to 256 sfx in one file (bank).
every time some one says "it should be enough" I remind him/her on the famous Bill Gates words "640k should be enoug"
Sure 1channel mostly work. I do 1ch SFX myself, most of the time. But we're talking short ingame SFX here. When ever there's a event SFX (like an explosion of the mothership for example) I use more than just 1 channel(!)
But we'll have SEE for that 
![afbeelding van [WYZ]](https://ru.msx.org/sites/default/files/imagecache/avatar-comment/avatars/picture-775.png?v=1470481363 "afbeelding van [WYZ]")
Yes, however: 1025=master, not 1024 