I can't tell you much about where Soundbox come from or even who they (apart from they are a four piece) are as even the t'internet seems unable to come up with anything about them. I can tell you what they sound like though, although given the suspect PA on the second stage at Dry Bar even that is proving a difficult task.
Soundbox have several things going for them, they have a great chunky bass sound, are all consummate musicians and in the nameless female singer/guitarist they have something of a star in the making. She has a great voice that just soars above the music and she has the look to go with it that just oozes stage presence. The delivery is good and they are pretty engaging although aside from the singer the rest of the band are a bit static.
The songs do have a bit of an edge to them but on the down side they aren't that memorable. There's certainly potential in there but you get the feeling they need some better tunes and a better stage show. They do let loose a little in the last song and they are all the better for it. Promising but work to be done.