RCA to XLR adapter, advantages of special boxes ??


Dear All i need to connect my CD player to a DAC converter. Doing this i would need an adapter S/PDIF coaxial RCA(CD)/ XLR(DAC input).
What's the advantage of boxes like the one below ??
Can't believe that such an higher expenditure does not bring any better music result, isn't ??
If the box is useless, could you give me a good adapter cable producer that will make the sound thrilling without pulling my legs ?? (range 50-70 USD for a pair)
Tks
http://www.midiman.net/products/m-audio/images/co3_lrg.jpg
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I don't know what claims are made for the box that your link leads to, but if all you need is an adaptor Purist Audio manufactures one that retails for $75.00.

The other option would be a RCA to XLR digital link such as (again) Purist Venustus, retail at $425.00. Probably less that the adaptor boxes you ask about.
There are several solutions besides the box you refer to. The advantage of the box is that there are so many options. Whether the box itself degrades the signal via poor connections, soldering, or switches would be a question I might be concerned with. There are more simple adapters that simply adapt RCA to XLR. The better ones are made by Neutrik and often come with BAT components (I think BAT markets the Neutrik adapters under their name). You can also find cheaper adapters at the local Radio Shack or electronics supply store. I don't know if these are identical to the BAT/Neutrik adapters, but they are only $10.49 each on this site, which is a world away from the BAT price, and they are made by Neutrik:
http://www.markertek.com/MTStore/product.CFM?BaseItem=NA2FPMM
You can also find some cable makers that will make, and do market adapter cables with RCA on one end and XLR on the other. Stealth Audio is one, and I use their CWS (cross-wrapped-silver) cables to go from my single-ended CD player to the direct input on my LS2B. Excellent cables, but would cost at least double your budget. They do come up used on Audiogon but still tend to go for more than $140 a pair. The adapters would be the cheapest solution. Remember XLR come in both male and female so make sure you get the right one for your application. I believe you'd loose the advantage of grounding that the XLR to XLR connection would otherwise provide if you are going from (or to) single ended. Someone correct me here if I'm wrong.

Good luck!
Your signal from the CDP is a single-ended signal. In order to get a differential signal for the AES/EBU specification, you need two signals, one non-inverted and one inverted. The box that you speak of generates these two differential signals from a single digital signal. The differential signal will give you more noise immunity and probably less jitter as well.