i'm very interested in this, except i'd love to keep the possibility of having OpenMPT adhere to a single hardware OPL3 chip as well, aside of the option with per-instrument OPL3 instances

This is in case somebody writes a module converter to formats that have real hardware replayers (think A2M), which isn't an impossible prospect, since i already know of one person who might be willing to do just that

You can easily constrain yourself to that by not using more than 18 channels and not using NNAs. As soon as you use NNAs you would be way outside of the A2M specs anyway. I don't really see any value in this limitation that cannot already be achieved in simply by writing a song that conforms to the hardware limits.

Fair enough, now that i think about it again

Note-Cut behaviour has been reworked in r11226: ^^^ cuts the note as expected, pitch/volume/pan can still be modified after note-off.

Behaviour was modified once again in 11233 as the legacy flag was not 100% compatible; the meaning of the flag was also inverted, if the flag is enabled, the more logical mode is used. The flag is now also disabled automatically when converting from S3M to preserve playback behaviour more accurately.

"The current model of modulator = filter cutoff, carrier = volume" Sounds like it should currently modify OP1's TL with a Zxx.

I'm not sure this is yet the case as of 1.29.10.00

It has been the case from the beginning, but the instrument mustn't be in Additive mode for that to work.

Okay for some reason my program was bugged and it wasn't working. I guess my previous method of installing over the old version and saying "yes" to replacing every file somehow lead to errors. A fresh install fixed it.

This use of Zxx should be documented in the docs.

Okay for some reason my program was bugged and it wasn't working. I guess my previous method of installing over the old version and saying "yes" to replacing every file somehow lead to errors. A fresh install fixed it.

Either you got an OpenMPT version with OPL support or you don't. It's extremely unlikely that the installation breaks in such a way that OPL works but only the filter modification doesn't.

This use of Zxx should be documented in the docs.

It is documented: https://wiki.openmpt.org/Manual:_Samples#Volume

It specifically only says "filter cutoff commands" because filter envelopes also work, and Zxx is a macro command so it can do other things than just setting the filter. The manual should not create the expectation that any Zxx command will automatically change the modulator. It is in fact very well possible that you maybe were using a default Zxx setup in your previous installation where Zxx by default simply didn't set the filter cutoff. In that case it's expected that modulator volume will also not be updated.

Maybe you've already thought about it, but wouldn't using multiple emulator instances cause trouble with OPL Export?

Yes, it's not entirely clear yet how that would be solved. VGM supports two instances of the same chip, but that's it. We could always fall back to single-chip usage for VGM export as an option, or export each instrument to its own file.

you can use 1-2, 3-4, 5-6, 10-11, 12-13 and 14-15 channel with OP4 mode