Nectarine

There are a couple of playback settings that can be tweaked. Normally they can be left on their default value.

Forced play time
Trim song length or loop modules. If the file is a module and this value is greater than song length, the module is looped.

Fadeout at end
Fade song 5 seconds at end. Useful for looped modules. Currently there is a bug that it's enabled by default and requires "Forced play time" to be set for this setting to take effect.

Playback mode
Tracker emulation mode for BASS replayer. I think this mostly affects frequency tables. If a module sounds out of tune, changing this might fix it. Usually this is detected automatically.

Playback interpolation
Resampler used by BASS replayer. Modules and chiptunes in partucular composed on the Amiga sound better with the "Off" resample. This is due to the aliasing which is similar to that of Paula chip's resampler. Sinc is the best quality resampler and used for all non-Amiga modules. FT2 uses a linear resampler, but so far I haven't found a module that needs it.

Playback RAMPAGE!
Sample volume ramping. It quickly fades in samples to reduce clicking artifacts. Some chiptunes might sound better with it turned off. Default is normal, and if I think there is no auto detection.

Playback Mix
Stereo dowmixing. Some songs have 100% stereo separation which need to be downmixed for headphone listeners. I think this might be set during upload.