Actually, I use Teflon insulated, single strand, twisted pair for interconnect. It's about 30 or 34 gauge. Yes, it's delicate, but it sounds simply wonderful and I didn't have to pull it through anything at all; it's just simple twisted pair. I've always meant to try it with a copper braid shield, but not from any real problem with noise or hum...just something I wanted to try. One of the reasons I haven't been too hot to shield it is that I can argue that the extra capacitance from the braid would do more harm than good--especially since I don't need it.
One other thing I've been meaning to try is a shield using the 'guard' circuit discussed in Horowitz and Hill. Kinda intriguing.
For silver wire without the hassle, try:
http://www.a-msystems.com/physiology/products/wire/coatedsilverwire.asp
They sell Teflon coated silver in a number of guages.
I've got a note to myself that surfaces on my desk periodically, something to the effect to try
http://www.medicalbuyer.com. I'll try to verify the address and whether they actually have Teflon coated silver wire.
My feeling has always been that silver is too chemically reactive to leave lying about without a good coating of something. Merely pulling it through a sleeve will insulate it electrically, but will do little to protect it chemically. Silver tarnishes easily (silver sulfide, if memory serves, but I wouldn't be surprised if there was also some silver chloride in there somewhere), and I'm not so sure how silver compounds sound. I'd just as soon let someone else do the Teflon at the factory whilst the wire is clean, so it stays that way. The stuff I've got is still pretty after fifteen years or so; not at all tarnished.
For speaker wire...I dunno. The idea of making a braided Litz wire occurred to me years ago, but it did seem like a fair amount of work. But for interconnect, you can't beat the sound for the price.
Grey