Long runs - USB or RCA???

No, sorry guys! Long USB cables are no, no. Go for the long ICs.

15 feet of USB cable isn't what I would consider long. I couldn't hear any differences between 15 or 6 feet of USB cable. I know several audiophiles that use similar lengths..no problems to speak of.

I agree with Gmood1, here size does not really matter....and Ultrafitimes, how did you come to your findings? Long ICs are certainly OK, but cost a lot more then even a good long USB cable. I tried both, but could not really hear much of a difference, so I settled for the less costly version. I am using a Spoiler USB dac, which driven that way is in the same league sonically as the Zanden combo or the DCS stack, as I pointed out elsewhere in these pages..... and yes, even a humble Trends USB to digital converter will sound perfectly fine that way, driven through the Zanden DAC.

I don't have any direct experience with it but here is some information from the usb.org FAQ:

USB Cables, Connectors, and Networking with USB

Q1: How long of a cable can I use to connect my device?
A1: In practice, the USB specification limits the length of a cable between full speed devices to 5 meters (a little under 16 feet 5 inches). For a low speed device the limit is 3 meters (9 feet 10 inches).

Q2: Why can't I use a cable longer than 3 or 5m?
A2: USB's electrical design doesn't allow it. When USB was designed, a decision was made to handle the propagation of electromagnetic fields on USB data lines in a way that limited the maximum length of a USB cable to something in the range of 4m. This method has a number of advantages and, since USB is intended for a desktop environment, the range limitations were deemed acceptable. If you're familiar with transmission line theory and want more detail on this topic, take a look at the USB signals section of the developers FAQ.

Q3: How far away from a PC can I put a USB device?
A3: With the maximum of 5 hubs connected with 5m cables and a 5m cable going to your full speed device, this will give you 30m of cable (see section 7.1.19 for details). With a low speed device, you will be able to get a range up to 27m, depending on how long the device's cable is. With a straightforward cable route, you will probably be able to reach out 25m or so from the PC.

Q4: I need to put a USB device X distance from my PC. What do I do?
A4: If X is less than 25m or so (see previous question), buy a bunch of hubs and connect them serially with 5m cables. If you need to go farther than that, put another PC, or maybe a laptop, out where you need the device to be and network it with the first PC using something that's intended to be a long-range connection, such as Ethernet or RS-485. If you need to use nothing but USB, consider using USB based Ethernet adapters to hook the PCs together.

i use a 30 ft usb cable to my dac, it sounds ok to me, all i can say is it sounds better than apple AE toslink to DAC