The title screen theme from Treasure Conflix. This was requested by Deeke.
Please note that if you want to use this in a level and don't want three channels to permanently disappear when you pause the game, you can either patch this to your ROM or open the .txt file of the port and delete every instance of $F4 $01!
How come pausing causes three channels to disappear here?
Legato. In the original, those three channels always have Legato enabled, which means the channels won't key off the first note (it essentially plays a very long note which changes its pitch). The original pause SFX keys off every currently playing note, which breaks Legato.
The patch I linked in the description (credits to KevinM!) makes it so the pause SFX sets the master volume and tempo to 0 instead of interrupting the song, this way it's possible to restore everything after resuming the game.