It's certainly possible to add it to the dropdown box. But what about the actual functionality behind it? g

OpenMPT is not an SNES emulator, and as such, there is no priority in emulating whatever the SNES hardware might be doing. I am not very knowledgeable about the internal details, but I thought the SNES got its characteristic sounds from the sample compression scheme used, and not from the filter type?

However, if someone from SNES community who actually knows their stuff about how the DSP works writes a patch for OpenMPT and verify that it sounds like the real thing, I would probably think about incorporating it, but I am not going to do my own research on SNES filters. However, this thread doesn't sound very convincing that it would be feasible to do this: http://forums.nesdev.com/viewtopic.php?t=6991