Take 2 light bulbs and wire them in SERIES - each will have 120V across it. Temporarily connect the USA transformer (off load) across one ot the light bulbs. Measure the secondary - my guess is 15V.
The amps will be the wattage rating of the device (the player should have a rating plate) divided by the voltage. i.e if an 30W machine then the primnary will be 30 divided by 240 = 0.125A and the secondary (if the winding really does provide 15V) 30W divided by 15V = 2A
Frankly I don't see it mattering too much - a transformer of about the same size will work - and it's very likely that any secondary from 12 to 24V should be OK - there will be circuitry to sort out the required DC voltages that should be able to cope with a wide variation of input volts.
Good luck...
Peccavi
March 2010