USB-S/PDIF Converter or USB DAC?


I've decided it's time to use a music server with my main system. I currently use one (iBook) with my headphone system with the Grace m902 headphone amp with built-in USB DAC. I intend to get a new Intel iBook when they are released (March/April).

I currently have an unused Wavelength Audio S/PDIF DAC that I could use with a USB-S/PDIF converter (such as Empirical or Red Wine Audio) or get a USB DAC (WA Brick, Stello, ???). Is a dedicated USB DAC preferred over the hack USB-S/PDIF converter route?
budrew
Does anyone have any experience or opinions about Toslink to coax converters (maybe it's an adapter and not a converter)?
What is the maximal reasonable length for USB connection? AFAIK after some length you have to put USB repeaters. It won't distort the data, but it may mess up timing, isn't it?
5M is the maximum length.

There's a great web site called "Google" where you can find out things like this or, it seems, just about anything.

Not sure what you mean about timing.
If any buffering involved, you may have delays resulting in pops and clicks...

So what do you guys do if the distance is more then 5m?
For more than 5m, use a USB-SPDIF converter first, then you can send a long way. Across the house. To the neighbors, even.

jh