To embed a SoundCloud track in to the text of your post you can use the SoundCloud icon now available on the Boardcode menu:
(If you don't see this icon press F5 to refresh your browser.)

Then insert your SoundCloud track link inbetween the BBCode brackets:This displays your track with the Play button and allows others to see any comments made on your track: Example:

https://soundcloud.com/scuffham-amps/confuse-the-cat-by-zabukowski