Hi Buddha,
Well I could not find any more information on the player, no response from the manufacturer, but I would consider less than 500 ohms output impedance normal. Others I have seen have been less than 100 ohms, but I believe you stated the component has been modified, so it could be higher.
Anyway, 100khz seems more difficult to comprehend than 20khz so I produced some data at 20khz using cirmaker.
Output Impedance (Z)----Capacitance-----DB change
2k ohms-------------------250pf cable--------0.017 db down
1k---------------------------250------------------0.0045 db
500-------------------------250-------------------0.001 db
2k ohms-------------------475pf cable--------0.061 db down
1k---------------------------475-----------------0.016 db
500-------------------------475-----------------0.004 db
One can compare the loss using each cable at 20khz and see the change is quite small. For instance at 1k ohms output Z, the change caused by swapping cables is approximately .0115 db.
Hope this helps Buddha.
Steve