Hmmm... Gordon is a very smart guy, but I would be very cautious about a 50' run of coax, esp. w/a couple grand price tag. I had a set up where I ran a 30' run of toslink to a DAC and switched from that to a 30' run of USB and a short toslink run, and the difference was night and day. I would note that the max range of a standard USB cable is like 20' or so--you have to use USB repeater cables, which receive/retransmit the USB signals, for longer runs. They are still relatively cheap ($15 for a 16' run), so it might be worth trying. If you do try the coax route, make sure its returnable if there isn't a sonic difference.
If you are talking about spending a couple grand, they may be other alternatives as well. This may sound strange, but if you have a Wi-Fi equipped laptop, you might consider getting a small form factor PC and a Wi-Fi access point. I use a Serener L02, from http://www.logicsupply.com, which sits on my stereo rack, and the USB out from the Serener goes into my USB audio device, then to my DAC, with very short runs of USB and coax. The Serener has no monitor, keyboard, or mouse, and just runs iTunes. Its fanless and with a NEC spinpoint drive, dead silent. I control the whole thing with a viewsonic airpanel--a Wi-Fi touchscreen that runs a remote desktop. But, there is no reason you couldn't use your laptop to be the remote desktop. In effect, you would have a virtual desktop for the Serener running on your laptop and be able to control the Serener with it. Seems odd, but it would probably run you only $1K, as opposed to the several $K for a 50' run of decent coax.
If you are talking about spending a couple grand, they may be other alternatives as well. This may sound strange, but if you have a Wi-Fi equipped laptop, you might consider getting a small form factor PC and a Wi-Fi access point. I use a Serener L02, from http://www.logicsupply.com, which sits on my stereo rack, and the USB out from the Serener goes into my USB audio device, then to my DAC, with very short runs of USB and coax. The Serener has no monitor, keyboard, or mouse, and just runs iTunes. Its fanless and with a NEC spinpoint drive, dead silent. I control the whole thing with a viewsonic airpanel--a Wi-Fi touchscreen that runs a remote desktop. But, there is no reason you couldn't use your laptop to be the remote desktop. In effect, you would have a virtual desktop for the Serener running on your laptop and be able to control the Serener with it. Seems odd, but it would probably run you only $1K, as opposed to the several $K for a 50' run of decent coax.