Long delay later...
I sort of managed to get some of these tunes working / not working simply as binary files, and just needed to load them in as such. VirtualAquarius emulator allows the loading and execution of a binary at whatever address you give it - (stating the obvious : same origin address as when it was assembled)
Those tunes that write back to memory, of course, will fail, since Im trying to run these in the cartridge ROM area.
CAQ cassette header:
Further looking and fiiddling has finally found the CAQ header, and a somewhat self creation of a BASIC loader for the binary. Just type RUN after CLOADing the CAQ file in.
Found the CAQ stuff within a few sub-directories of James Tamer's VirtualAquarius emulator.
The header is here for future reference :
https://github.com/bushy555/Aquarius_1- … uarius.asm
...however in saying this, Shiru's "LetsGo" is ~15k, and I can't get it working with this header, either in VirtualAquarius or MESS emulators. This CAQ header though seems to work fine in many other programs - perhaps it has an 8kb limit?
I've managed to sort of getting "LetsGo" working in the VirtaulAquarius emu just by making its origin at $4016, and executing it here. I'll attempt to get a video of it when I can get it working next.
(There are BASIC pointers and variables stored at $4000-ish, hence the $4016).
Weirdly though it works maybe 2 out of every ten times I try to load it in, even after killing the emu and restarting it.
Clearly Im still doing something wrong somewhere. Doesn't matter - I love me fiddling around.