Since reading your reply I have had a look around at what you suggest, These powered usb hubs appear to be available with ext pwr supplies. This may be the way to go.
I had one other issue with the DSI, ie. the connecting cable was to short and the use of a passive high speed usb extension immediately generated an error, I ended up with an "active usb extension cable" which solved that problem (at a slightly more expensive cost).
Thankyou for your reply
Arthur Alchin
