That's another feature that makes this "better than soundcloud" because they don't provide a volume adjust on their site.

Really annoying for those times when I've been playing soundcloud in the background with some other audio source in the foreground (like a video game, or even just mail notifications going beep)

They do, but its in the top-right corner of the page. Took me months to notice.

You're awesome, thank you. I would have never found that.

We're so conditioned to look for the volume UI to be near the play button.

yeah agreed, i have an in with some of the devs on this - the volume slider was a secondary feature and is on the list last time i heard, stay tuned (haha) for the next release,