I'm using some Puresomething_or_other Belkin optical cable w/mine...
Was a tight fit but loosened the split ring connector on the cable a smiggen & used a spec of dielectric lube & its all good. Often use a bit of that lube on any connectors that are plugged/unplugged frequently. Here's it w/the Buffalo32s & 4-ch beta22 still on the bench:

Got the Onkyo in 10 days from that big ebay seller of them in Japan. Wish they had black but was told black was not available in Japan. But @ the price silver is fine by me:)
Working well & as described in English manual (found online) w/my 5.5G iPod (have to use iPod button to get control of iPod, but remote buttons like prev/next work & that's the main thing).
Edited by cfcubed - 12/8/10 at 5:20pm