'''Solved''' - After turning the volume '''up''' on the laptop and '''down''' on the JBL speaker (so same overall volume) the speaker no longer cuts out every 10 mins. Perhaps has something to do with the level of sounds that the JBL speaker is receiving through the cable which is putting it into a sleep mode. Regardless, this has solved the problem and it no longer goes silent every 10mins, thank goodness.
(HP Elitebook laptop, JBL Onbeat wifi speaker, and connected through an AUX cable)