Hum in CD player after voltage switch

Hello all. This is my second post and am still a newbie. I recently purchased a Roksan Caspian CD player from a fellow in Germany. The player was set up on 230v when it arrived and I immediately shipped it off to the Roksan US distributor to perform the voltage switch to 115v.

I received the player back from the distributor today and immediately hooked it up. Everything plays fine except for a medium loud hum coming through the speakers. I have tried everything I can think of to isolate the hum and it definitely is related to the CD player. I've tried different power cords, different circuits, audiio cords, swapping out with the old CD player, hooking the new CD player to another amp and there's no getting around it...the hum comes from hooking up the Roksan CD player no matter what I try.

Is there something tech support could have been missed in switching the voltage from 230 to 115? TIA for any suggestions.
Is'nt there a 'ground' error. Maybe the CDP has a ground pin in the IEC socket that connects your whole system through there to "earth". This is a very commin problem with audio-equipment. Ground-loop error. If all the equipment is "ground-lifted" exept for the CDP there may enter hum. Or maybe the guy got you for a sucker - the machine may be faulty. It may also be that it is a 50Hz machine on a 60Hz grid. With 240v we have 50Hz...

Check all your ground connections - take a lead and disconnect the green/yellow wire inside the plug and try it out.

Kind regards,
Dewald Visser