Audio connect from PC to analog receiver

The PC has a 2 channel, female, audio out line for minipin and a similar looking one (Toslink?) for SPDIF. Non-digital receiver has white and red RCA females for audio in. Using the analog out results in a persistent speaker buzzing that sounds very similar to the audible running sound of the PC.

Two possible choices:

1. Change out the Sound Card and use the analog. Recommended sound card?

2. Use the SPDIF. Search shows that their are optical and copper wired SPDIF cables but no adapters to the receiver’s analog requirements and input connectors.

Which is most likely the better option and, if SPDIF, are there adapters to the receiver.

Thanks for your fast response, Abe