libopenmpt by default enables extra-smooth volume ramping for XM files made with FastTracker 2 - the very same way as FT2 would play them. This effectively kills the attack of many samples, making them sound a bit duller and less sharp. OpenMPT does not enable extra-smooth volume ramping by default, but can be configured to behave the same way through the hidden setting Misc.SmoothFT2Ramping.

For libopenmpt, this setting can currently not be turned off.

Thank you very much for the explanation. Is there a reason why you don't add the option to turn this setting off? When I open this song in Milkytracker or Schism, the mentioned instrument is also louder/crisper like in OpenMPT, so it seems libopenmpt is the one sounding different.

btw I got it working on my fork, i.e. disabled kFT2VolumeRamping
If it makes sense, I can create a PR to allow callers to disable the FT2-extra-smooth volume ramping.

I created this PR https://github.com/OpenMPT/openmpt/pull/34 so you can check when it's possible for you, but this might get out of my radar in a few days so I just leave it there now while it's fresh :)

Thanks for the pull request. We will have to think about whether this is the correct approach though, please see the related issue for more information. This is by far not the only playback setting that we should expose, so choosing the wrong approach to do that now might just lead to more complications later.

I agree that when you want to expose more flags, this need to be thought through. If you know which flags shall be exposed, I can also think and suggest a way to go.