Coaxial or Optical?

mypersonally thoughts are, if you are going anywhere near / along power lines, there's no question, go optical.

there are tons of arguements re: sound quality from optical vs, coax, you could have a coax cable made of belden 75ohm cable w/ good connectors for fairly cheap (certainly cheaper than optical will EVER be) but of course being copper-based its' more prone to interference. even if some people feel copper/coax will yield a better sound, i would think that improvement would be far outweighed by data loss / interference.

i did a similar install and am using a 12m audioquest optilink 1 (about a $300 cable in this length) and love it.

It has been argued that coax generally sounds better than optical.

You can buy very long lengths of optical cable on e-bay. These cables vary in quality, but are quite affordable. My roommate purchased something like a 30 or 50ft cable for $40 to connect his laptop (built in toslink) to his receiver (an entry-mid level HK) powering a pair of Paradigm monitors (~$200 but I forget which ones). He has been playing compressed MP3s via this setup, but at this level the sound quality has been perfectly adequate (hooked up an AQ toslink as well and heard no difference). In the uncompressed file situation you speak of differences may be audible, but at the potential cost of your 35ft run it may be worth considering evaluating a cheaper cable (and returning it to ebay if it sucks).