Digital interconnect
For an interconnect between a cd player and DAC, or an amplifier with a built in DAC, which is the best, ( in terms of sound quality), a Toslink optical or an RCA digital ?
I think the slight majority would say digital coax, but some do prefer optical.........but it's by no means an open and shut case.
I was always under the impression that coaxial is sonically better than optical, though I personally haven't tried optical.
I doubt there can be much in it, it's an on or off signal with no variables. I think any differences would be all but in audible.
They should sound the same. But if I were to choose, I'd go optical as there is zero electrical connection, and potentially less inteference. But I can't say I have ever heard any difference.
This is purely my experience!
I found optical a bit more analouge sounding and this is what I use to connect my Apollo R to my DAC
I have a 1m Chord Prodac between CDP & DAC but it hardly ever gets used. My TV's sound is through a 3m basic optical & my ATV via a 0.5m optical. Some say optical is better than coax over longer runs. Personally, I've heard no difference between the two.
I've occasionally connected my laptop to my DAC via USB that's unusable unless the laptop is not powered through its switch-mode PSU! This highlights why under certain circumstances that optical is best - galvanic isolation - a technique used in a lot of non-audio electronics to remove damaging earth currents.
Hasn't anyone found the difference to be 'Night And Day'? 
Doesn't anyone want scientific proof?
In the pst it has been mooted that a co-axial (electrical) digital interconnect is best for short runs, e.g. from a CD to a DAC, etc., whereas a fibre-optic is better for longer runs.
The signal from a CD starts out as optical, and is then converted into electrical for the on-board DAC in a CD player. For an electrical interconnect, this data stream just gets fed into the interconnect, off to the DAC for processing. If you use a fibre-optic, the signal gets converted back into an optical signal inside the CD player / transport, then fed along the fibre-optic (with a potentially more "lossy" junction at either end), into the DAC, where it's converted back into an electrical signal for processing by the DAC.
So the electrical route:
CD (Optical) --> Electric Digital Cable ---> DAC
The optical route:
CD (optical) --> Electric Circuitry ---> Electrical to Optical Converter ---> Fibre Optic Cable ---> Optical to Electronic Converter ----> DAC
So with the optical route there's two extra conversion prcoesses involved, which MAY increase the risk of data error and jitter.
I also find electrical interconnects a bit more robust physically, so if you're in the habit of connecting and disconnecting stuff, an electrical interconnect might be better.
ON THE OTHER HAND:
For long runs, I prefer fibre-optics. The cables are a lot cheaper, especially for long runs, mechanically more flexible and the sources, e.g. my satellite box, and the destination, e.g. my surround sound, aren't as crticial as my hifi listening.
Just my opinion, naturally.
I find the coax to be the best , chord signature. I have tried optical but I did not think it was as good. A good hi fi shop should give you a demo of all your choices.
There are many that will say its just a big load of 0's and 1's so how could it make a differance but it does.
In the pst it has been mooted that a co-axial (electrical) digital interconnect is best for short runs, e.g. from a CD to a DAC, etc., whereas a fibre-optic is better for longer runs.
The signal from a CD starts out as optical, and is then converted into electrical for the on-board DAC in a CD player. For an electrical interconnect, this data stream just gets fed into the interconnect, off to the DAC for processing. If you use a fibre-optic, the signal gets converted back into an optical signal inside the CD player / transport, then fed along the fibre-optic (with a potentially more "lossy" junction at either end), into the DAC, where it's converted back into an electrical signal for processing by the DAC.
So the electrical route:
CD (Optical) --> Electric Digital Cable ---> DAC
The optical route:
CD (optical) --> Electric Circuitry ---> Electrical to Optical Converter ---> Fibre Optic Cable ---> Optical to Electronic Converter ----> DAC
So with the optical route there's two extra conversion prcoesses involved, which MAY increase the risk of data error and jitter.
I also find electrical interconnects a bit more robust physically, so if you're in the habit of connecting and disconnecting stuff, an electrical interconnect might be better.
ON THE OTHER HAND:
For long runs, I prefer fibre-optics. The cables are a lot cheaper, especially for long runs, mechanically more flexible and the sources, e.g. my satellite box, and the destination, e.g. my surround sound, aren't as crticial as my hifi listening.
Just my opinion, naturally.
I have never seen it explained like that before..............so very enlightening
They should sound the same. But if I were to choose, I'd go optical as there is zero electrical connection, and potentially less inteference.
Aha! That might be the case, but natively the signals are electrical not optical, and surely there's more chance of errors creeping in as the signal is converted too/from light than it has through the most bog-standard electrical cable.
Just threw that in there for the sake of discussion...
Just to add, I'm more confident of a "good" electrical connection than a fibre-optic one as well. And remember, there's one at each end of the interconnect, whichever way you go.
For an interconnect between a cd player and DAC, or an amplifier with a built in DAC, which is the best, ( in terms of sound quality), a Toslink optical or an RCA digital ?
I regard the thinking, so far, in this thread, to have been clouded.
The OP is re-stated above, and imo should be re-considered.
Firstly a digital data stream does not possess 'sound quality', - that is a quality which can only be applied to an analogue signal, ultimately used to convey a signal to a transducer such as loudspeakers or headphones and which human ears can audibly detect or appreciate.
You can't listen to digits, and digits don't have sound quality, since all digital data is merely a string of information which is no different in character whether it carries text, numerical information, video, or even computer program instructions.
The only time 'sound' is produced from digital data is at the converter stage (output) of a DAC, when a new analogue signal is generated from the data. By then it is irrelevant how the digits arrived at the DAC, whether it be by ethernet, digital wireless stream, internet distribution, toslink cable, s/pdif co-ax (RCA), or whatever, as long as the digital stream is not corrupted.
JC
Good post JC. I think the question the OP is asking could be rephrased as "Which S/PDIF connection, out of toslink and Coaxial is more likely to introduce errors?".
IMHO, the answer is that for all practical purposes, cable introduced jitter just isn't a problem*. Use toslink if you can as it gives electrical isolation between components.
*It's another theoretical problem the hi-fi industry has used to sell expensive kit that solves a non-existent problem.
*It's another theoretical problem the hi-fi industry has used to sell expensive kit that solves a non-existent problem.
I knew someone would want scientific proof. Now I just need someone to say the difference is night and day.
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It depends on what you are connecting and what you are using to connect...as sound quality is subjective. I have connected my SL-P333 to my RA-11 using both an optical & analogue cables and personally I find that the sound quality/musicality of classical & jazz are better via the analogue whilst for more 'pop' (excuse the term) the optical sounds better. But that is just my set up.
Remember also that what you will be comparing is the DACs (the one onbaord the CD player vs. the external) and so in some respects the cable comparison is not really a fair one IMHO.
Personally what I would do is connect up both as I have done and then decide. If yo do not want to spend the money then see if yo can borrow the interconnects yo are considering and audtion them before making up your mind. I have kept both connected (as mentioned above).
EDIT: Apologies...misread the OP...please disregard this contribution as it is not relevant.
Rotel RA-11 | Technics SL-P333 | Rotel RT-11 | Technics SL-L1 | KEF Q300 | Grado SR80i | Atlas & QED interconnects