Digital Cable Choice; how critical is it?

You said:

"considering that the digital information that runs from the DAC to the Preamp is 1's & 0's or bits & bytes or whatever they are called;"

didn't you mean the (single) cable that runs from the CD transport (or digital output of a CD player) to the DAC?
And yes it does make a difference.

It's also important what kind of analog IC's you use from the DAC to the preamp and whether they're single ended (RCA) or balanced (XLR). Balanced seem to work better if your preamp has balanced inputs.

It's also important what kind of power cord is used with DACs, CD players, or basically anything with digital processing circuitry in it (meaning even preamps with digital volume controls). It has to be shielded, and it seems that with most digital-to-analog equipment, bigger (wire size) is better for sonics -- although I still can't explain why, because DACs aren't power hungry like most amps.

I also prefer fiberoptic cable (glass AT&T, not plastic Toslink) to metal coax (S/PDIF, RCA, BNC) or AES/EBU (XLR) for a number of reasons, not the least of which it isolates the DAC from the transport electrically. Unfortunately, there's only one really good one and it's a thousand dollars. Three thousand if you own EMM gear, and have enough money left over ;--)
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I don't know if Kubala makes digital (75 ohm) ICs, but if they do, stay with them (for RCA or BNC which is the 75 ohm I'm talking about). Otherwise, if you have AES/EBU connectors on your DAC and CD transport/player, those are always preferred over coax S/PDIF (RCA) or BNC (bayonet) IMO. Kubala has those I'm sure.

I don't know about that "CD direct" business. If your new preamp also has balanced inputs, I'd try it both ways. Betcha a new CD you like the XLR better ;--)
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Hi Mike -- That's not a surprise. Glass Toslink has almost twice the bandwidth as plastic. But its practical length is still only 5 meters, while AT&T ST cable can go up to 100 Km between repeaters (for those REALLY large listening rooms ;--)

The real issue with Toslink (for audio, that is) the poor quality of the little transceiver units. They cost about $5 wholesale (STs cost about $120 wholesale) and the quality of their signal output is affected by end-to-end reflections in the cables (another reason to use glass if you can) and transmission jitter (glass won't help with that.)

It can't ever beat AT&T, but whether a glass Toslink connection would outperform a high quality coax (RCA) or aes/ebu (XLR) I really don't know. It would be easy enough to try though, because today, almost all stuff that has Toslink has coax inputs/outputs well.

Here's a little Toslink history if you're interested:

http://www.audioholics.com/techtips/audioprinciples/interconnects/toslink.php
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Are all of you (Tobias, jeffcott, Jeff_jones) referring to a lack of difference only between 75 ohm cables (either RCA or BNC), or ALL digital data cable including 110 ohm XLR. ST glass, and Toslink (plastic and glass)?
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Jeff, thanks for the link. I enjoyed the presentation.

Have you used this device to measure the things you mentioned in your audio system, or it it strictly a work tool?

I've never used anything but AT&T glass. For one thing, the Wadia DAC I used to have just had one glass input! (My new one has several different kinds.) I did try a lot of different AT&T cables though without any impressive differences UNTIL I sprung for an Aural Symphonics Optimism V2 and WOW! What an ear opening experience that was, with slightly different tonal balance depending on which way the cable was oriented. I know, according to your measurements, that should have no effect -- and it didn't with all my other ST cables.

As for 75ohm jobbies, all I know is what I've heard about connectors -- that BNC connections maintain the 75ohm continuity better than RCA connectors and therefore provide a more accurate datastream to the chips. But I don't use metal, so I haven't ever compared.
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