tyvan

HI!
I have a lexus 1996 LS400, I brough a glove box cd changer, there is an used OEM cd changer part# 86270-50100 but as I know the manufacturing part# is 86270-50090, could you let me what's the different?( the part# 86270-50100 has an extra box on back #86240-50010 made by nakamichi !, with out this box the changer work, but no sound, I have to connect the cd changer pre wire to this box and plus the wire from this box to cd changer it will work ok! but the sound not so perfect !) my car's sound system is pioneer, the cd changer also pioneer. please let me know why the pioneer cd changer(86270-50100) need an extra box from nakamichi? if I don't use this box is there any way to make the changer work?
thank you!
ty van