I got my Standard last week - enjoying it immensely. I also thought I was being clever scoring a cabled power kit from you-know-where in Germany, as they're pretty hard to get hold of in the UK at the moment. The XPS box is supposed to work with the Standard - even the salesman who sold me the guitar said this was the case, though they didn't have one in stock. However, while it does indeed power the Variax, some very unpleasant digital noise appears after a minute or so of use. I've tried switching TRS cables, output cables, different amps - same issue. Any ideas?