Thanks for the guidance, truly appreciated. Yes Noel I have made sure no mutes are ticked. What I have not thought about is the main mix slider on the Alto. I have it down to zero. For some reason whatever I thought that this would only control the XLR/jack levels to the powered speakers and not the USB level. The master level pot on the Wharfdale has also been turned right down.
Going to try the Alto again using the main mix slider. If I cant get that right I'll switch off and reboot again.
Take care.Bryan.