I think it'd make lots of things easier if you could put soundcloud players in posts, check:

http://blog.soundcloud.com/2009/07/28/soundcloud-player-in-forums-5-step-guide-for-soundcloud-bb-code/

why? who uses soundcloud?

there's no Add new Bbcode in the phbb admin, at least in this version
if you guys need it I can add the string manually

I'm not entirely sure what soundcloud even is !

disable guest posting now you are at it

pretty much everyone uses it, but i don't know about this forum
it's a very useful service and something that's finally seems to be replacing myspace for music.

There really isn't much artist self-promotion in this forum to warrant the need for it imho.