Long USB Cable OK?


I just purchased an Ultra Fi iRoc DAC (haven't received it yet), and intend to use it with a media PC that has iTunes (I've all my CDs on the HD on Apple Lossless format).

Question I have is whether it is ok to use a long USB cable from my PC to the DAC? Currently my PC is about 18 feet from my Audio System. I can then connect the DAC to my Preamp with a very nice analog pair of ICs (1M pair of Acoustic Zen Absolute - I think retail on those was about $2.5k). Also, can I use a regular length USB cable and an extender (I have an extender already, so am just wondering if I can use that too, without any sonic impairment)?

Alternatively, I have a very long length of cheap analog ICs I can use (and keep the DAC close to the PC with a short USB cable).

I keep the PC out of the way because its noisy and prefer not to have it alongside the audio system and speakers.

Any advice welcome. Thanks!
John.
128x128outlier
Lokie -- Thanks. Interesting that he's recommending considerably shorter lengths than the usb2 spec specifies. Good to know.

Regards,
-- Al
I build my own computers, and the quietest cases I am aware of are some of the Antec's, including the P180 and P182 models, and possibly (although I'm not certain) some of their more recently introduced models.

You might find this site of interest:

http://www.silentpcreview.com/

If you don't build your own computers, there are lots of custom builders out there, findable on the web, who I'm sure could make a very quiet computer, using these or comparable cases. You might also want to consider transferring the innards of your present computer into one of these cases, assuming that:

-- The computer is reasonably contemporary and performs satisfactorily.
-- The computer uses a standard ATX motherboard (Dell's, in particular, often use non-standard motherboards, and possibly power supplies as well, that will not fit into a standard case.
-- The computer's internal noisemakers that are not part of the case (cpu fan, hard drives, power supply, video card) are not unreasonably loud, or would be replaced with quieter counterparts.

Regards,
-- Al
The new flat WireWorld USB cable can handle lengths up to 7 meters. I have a 1.5m and 5m in my system and I can't hear a sonic difference between the two cable lengths like some other cable brands. BTW, the sound quality is superb compared to other cables (Kimber, Belkin Gold, Monster) costing the same price.