DDJ-1000 & Windows 10 Sound Issues

Somebody please help... I have a DDJ-1000 that works beautifully with my MacBook Pro. I bought a reasonably high end Windows 10 laptop as a back-up... a 15" HP Spectre 360 with i7, 16GB & SSD.

Rekordbox is unusable for me on this machine. The sound is distorted, speeds up - is maybe then ok for a moment and then buggered again. I have scoured the forums, turned off indexing, dropped the max processor state to 99% etc etc. Nothing works.  To make matters worse, using Serato & my older SX2, the Windows 10 machine works just fine.   

Anyone, please help - this is massively frustrating.

Thank you !