There is only one time this dungeon theme is used in Phantasy Star 4 and it's before a crucial plot point, and it's pretty groovy.
It's a high quality sound upgrade with some reinterpretation with Jazz Stacks. It's a rinse and repeat, with a trimmed end so you can Loop it if you like. Saves me the trouble of a fade out lmao.
I made this in about an hour and tried experimenting with EQ and mixing. Enjoy!