OK folks, pleased to report the saga is finally over!!
dougho needs commending for holding out for a driver issue......... Well done!!
My Vendor changed the driver I was using, to the Realtec driver and the problem was solved.
My Creative T20's sound great.....
Many thanks to all the members, who had the interest and took the time to comment.
I've read somewhere recently, (can't remember where), that you HAVE to use the Realtec driver for the NUC front panel (ie: no other driver will do)......I don't know if this is true, so don't quote me on it.