I've just repaired a SCD Rom, and yes it was the capacitors. Every single one looked fine, no leaks, no corrosion at all, but after replacing 6 of them under the jumper board, right next to the AV port it was perfect! I did encounter one problem where the customer was using a power bridge connection for the SCD Rom and Core Grafx, The power hungry SCD Rom really needed that 12 Volts of power! It stopped the sound working fully when using this connection.
He then used separate connections for both units and found no problems after that. really should have taken pictures so I could have identified the caps for you all. But they are the same as usual 2 33uf and 3 100uf caps. Don't quote me on that, but I'm almost sure.