I just had a member (jkm78) on this list make me a cable. His company charged a very reasonable $20 excluding shipping. The cable will arrive on Monday.
This is a six inch long cable made with Mogami 2330 cable. It has a straight 1/8 female connector on one end and a right angle male connector on the other end. The right angle end of course will plug into the 'line in' jack on the R-09 and I plan on leaving it plugged in all the time to prevent undue 'line in' jack stress (even though the jack has been worked on by Edirol). I will bend the cable down around the body of the R-09 and secure it in place by wrapping one or two velcro straps around the body of the R-09 so that the cable is snugly hugged to the body of the unit. An alternative is that I may tape the cable slack to the body of the R-09. The tape of course will be stuck to the body of the R-09 on the back underneath the AGC, Low Cut, etc switches.
Obviously, with this cable attached, for each show I will plug into the female jack on the cable instead of the jack on the R-09. Hopefully this will enable the R-09 to last as long as I want it to.
You asked if there should be any sound degradation...I'd think that as long as you use good quality connectors and quality cable, there should be no reason the sound quality should be affected. However, I'm no expert.
I highly recommend contacting Justin (jkm78) if you want a similar cable or if you need any other cables. Not only are the prices excellent, but the turnaround was only a day or two.
Hope this helps!
Steve