Max length optical & mini cables?

Greetings!
I have a PC with a Chaintech AV-710 sound card. I have connected a set of Logitech Z-5500 speakers using optical cable. They work great.

I also have a Sony STR-K7000 AV receiver in another room. The receiver has an optical input and also RCA inputs for 5.1 sound.

The sound card has "mini" (1/8" or 3.5mm) stereo outputs to connect to a 5.1 system in addition to the optical output mentioned above.

I want to connect the sound card output to the AV rcvr in the other room = about a 50" cable run.

1) Can I connect with such a long cable run?
2) Shall I use optical cable or mini to RCA cables?
3) Where can I obtain such long cables?

I would prefer to use the mini to RCA cables to connect to the rcvr because I have had some trouble trying to connect the "mini" cables from the sound card to the Z-5500 speakers.

Thanks in advance for your sage advice!

Doug Stewart

Wow! Thanks, Rupert! So cheap, too!

Now, I'll have to figure out how to make the mini connections work with my Z-5500... We'll see...