It a gamble but I've bought a ML390s in the US and did the conversion myself. There was no password code and it was as simple (for someone who studied older electronics, like my father) as moving a jumper to the correct position.
If you look closely at the following picture: http://www.marklevinson.com/image_library/390SOH.jpg you'll see a white jumper block (8 positions) with copper jumpers. On the picture the jumpers are currently set at 110v (starting from the top that's (2/3 and 5/6)) and should measure something like 27 ohm between line and neutral (that's where the voltage cable goes in).
For 220v there only needs to be one jumper between 4 and 5 and this should measure around 98 ohm. For the 240v configuration one jumper should be set to 1 and 2 and should measure 109 ohm.
Cheers,
Alexander
If you look closely at the following picture: http://www.marklevinson.com/image_library/390SOH.jpg you'll see a white jumper block (8 positions) with copper jumpers. On the picture the jumpers are currently set at 110v (starting from the top that's (2/3 and 5/6)) and should measure something like 27 ohm between line and neutral (that's where the voltage cable goes in).
For 220v there only needs to be one jumper between 4 and 5 and this should measure around 98 ohm. For the 240v configuration one jumper should be set to 1 and 2 and should measure 109 ohm.
Cheers,
Alexander