In the game the music is stored in a 44100hz file, but the actual music frequency is 11025Hz

Once you resample it, it sounds low quality, the game resamples it using an interpolation something around 2-point linear and 6-point Hermite, giving it the iconic degraded filter

I cannot find the actual resampling filter used, however you can EQ the sound created from the resampling (Frequencies above 11025hz) to sound the same as the mp3 in the soundtrack files

I applied it to the game tracks

Track no. 14, 11 are looped