I long time ago when I was young, I was playing Super Mario Bros. 2, just messing around. I stumbled upon a trick that I haven't, to this day, met ANYONE WHO KNOWS OF IT!
The trick is, you get a Starman right before you enter the Sub-con door, (the one you get when you hurl the bubbling red potion on the ground). You wait about a "one one-thousand, two one-thousand", and enter Sub-con (it will probably take a few times). By the time the Starman music stops (while you're still in Sub-con), Sub-Con's music (old Mario theme) just starts... as you leave Sub-con, (if timed right), the music continues to be (a FULL version) the old SMB's music as heard in Sub-con... it lasts until you enter a situation where the music is set to change (i.e. Birdo encounters). Try it... it can be done on the first level!!!
Tell me there are other people out there who know of this! It's such a kickass little trick, I wish more people knew of it.
It DOESN'T WORK FOR SNES GAME, I don't think!