well, /splay -m filename ..
eg.
/splay -m "C:\Documents and Settings\Tom\My Documents\Scores\Andromeda Soundtrack\Andromeda - 02 - High Guard Theme (Season 2 Main Title).mid"
produces:
* /splay: unable to play 'C:\Documents and Settings\Tom\My Documents\Scores\Andromeda Soundtrack\Andromeda - 02 - High Guard Theme (Season 2 Main Title).mid'
Rename the file, and use:
/splay -m "C:\Documents and Settings\Tom\My Documents\Scores\Andromeda Soundtrack\Andromeda - 02 - High Guard Theme.mid"
and it's fine. So it's a filename length problem.
Through futher testing, I have worked out that the maximum length /splay works with is 55 characters.
Is this a mIRC bug, or a problem with the windows filesystems in general?