hey Grungeman,
I asked myself the same question some time ago, but in the great video recording of the Underworld show (London, Sep. 4th, 2000) he himself tells the crowd that his new album (back then) More Light by J "Mass-kiss" and the Fog will be out soon.
So I take that as the "right way" to pronounce his name 
…by the way, if you haven’t seen this fine recording of the Underworld solo acoustic show, yet, – it’s available for download on FreeSoFree.net (not only because of the pronounciation question
)