after struggling for a couple days to find the ideal setup for sifting through all these MIDI loops i’ve amassed, i’ve figured this out:
In WinAmp, go to Settings > Plug-Ins > Input > Nullsoft MIDI Player
first tab / Device tab, set device to DirectMusic / Microsoft Synthesizer (with output) (this fixed the volume issue many experience with WinAmp)
Misc Tab, set “Looping” to “Always” and check the “Infinite” box (this fixed the issue with the regular “Repeat” function leaving a slight pause between each repeat)
now any MIDI files will seamlessly and continuously loop in WinAmp until you start the next one
nothing too fancy but i’m EXTREMELY picky and have tens of thousands of loops to sift through at the moment, so a setup like this was necessary for my sanity