Compatibility question regarding a Chord 2Qute and a PS Audio Perfectwave Transport


After much deliberation I've decided on a 2Qute DAC and have located a used one in good shape.
My transport is a PS Audio Perfectwave memory player. I didn't think much about the compatibility of these two units until just now, when I'm about to buy the 2Qute.
....Here's the issue:
The PS Audio transport output options are (in order of quality according to the company), I2S, S/PDIF via balanced XLR, Coax via RCA and the optical.
The 2Qute's inputs options are: USB, BNC Coax and TOSLink optical.

Here's my question: From my reading it seems the 2Qute does much better with a USB input (the only input that's galvanically isolated).  Some go so far as to say if they had to use only the coax input on the 2Qute, they wouldn't want this DAC.
While separately the PS Audio transport and 2Qute are great, combining them forces you to use the coax connections which, on both units, are sub optimal.
....So you have two units that are pretty decent on their own and them combine them and have to use the least SQ optimal output/input.
Am I looking at this correctly?
Is this combination self defeating?
Kind of bummed as I was getting myself pretty sold on the 2Qute.
Thanks.
--My speakers, amp and preamp are Magnepan 1.7's, Butler TDB 2250 and a Modwright.
andrew-benn
I owned a QuteEx and used BNC coax from an ARC CD transport and the DAC sounded damn good; very much like analogue. Finding the right cable was key. Try to audition some BNC to RCA coax cables.

The PS memory player will output a better asynchronous signal than my CDP.

Is there any option to use some kind of adapter to mate the PS Audio S/PDIF (balanced XLR) output to USB input on the 2Qute?
--I'm completely un-knowledgeable on this subject and don't even know if such a thing is possible and/or exists.
The typical digital XLR output is AES standard...110 ohms. Are you sure that the output is XLR/spdif? 
Usually a XLR AES transformer is used to convert AES to spdif coax. But if your output is truly a balanced XLR spdif, then call PS audio or Google XLR to BNC 75 ohm adapters or cables.

The great thing about your setup is that the PS transport samples the CD to an internal buffer and then outputs it. The Chord DAC also samples the incoming data to a buffer and then reclocks it. That's why I think  coax will work just fine.
I guess I’m caught up on all the mentions I’ve seen of the 2Qute doing so much better with utilizing its USB input that ...it gave me cause for concern. I wanted to see if what others thought as up to now it’s just been CDP’s and 2 channel audio.
Moving into DAC’s and a separate transport is all new territory for me.
Did u check to see if the XLR output is 110 ohm AES ? I'm curious.
The Perfectwave transport is a brilliant design.
The PWT is excellent sounding via rca coax, just use a good quality cable. For the Chord if you question their coax output quality just get an USB to coax adapter. Why would the Chord coax be "inferior "? I’m skeptical of that assertion. I'm inclined to agree with low rider and believe a straight coax link should sound fine  (with a good quality cable).
Charles
I’m doubtful that connecting to the USB interface of the DAC would be practicable or even possible in this case. While of course there are many USB-to-coax adapters that are available, I don’t know of any adapters that convert in the opposite direction. A device providing a USB output would have to either be a computer or somehow emulate a computer’s USB-related functionality. And if there are such devices I would question how well they perform.

Lowrider, as I interpret various statements in the manual for the PWT its XLR output appears to simply be balanced AES/EBU, presumably 110 ohms. I say that despite there being some potentially misleading statements about the signals on that output being "S/PDIF encoded."

I have no first-hand knowledge of either component, but I wouldn’t be surprised if Charles is correct in anticipating that a straight coax link with a good quality 75 ohm digital cable (preferably RCA to BNC, or alternatively RCA to RCA + an RCA to BNC adapter) would work fine.

If you decide to proceed in that manner, it may be a good idea to ask PS Audio if they would recommend a particular length for the digital cable. The optimal length may depend to some extent on the unspecified risetimes and falltimes of the signal provided by the transport, among other variables involving the cable itself and the accuracy of the impedance match between the cable and each of the components.

Regards,
-- Al

Hi lowrider57,
From the PWT manual describing the outputs,
"The PWT offers multiple digital output choices including: XLR (AES/EBU), RCA and TOSLINK (S/PDIF) as well as I�S"

And in discussing the XLR output it further states,
" XLR. This is a balanced S/PDIF encoded output that complies with standards set by the AES/EBU (Audio Engineering Society/European Broadcasting Union). This can output up to 192kHz 24 bit data "
Here's the PWT manual link,
http://www.psaudio.com/wp-content/uploads/2011/11/PWT.pdf

In my original post, I got the " S/PDIF via balanced XLR " comment from a stereomojo review you can read here, http://www.stereomojo.com/PS%20AUDIO%20PERFECTWAVE%20TRANSPORT%20AND%20DAC.htm/PSADUIOPERFECTWAVETRA...

As this stuff is new to me, the quote I pulled from the stereomojo article could very well be "off".  --I wouldn't know the difference.  ....Although I'm starting to pick some of this up.
How do you read the PWT manual and what it says about XLR output?
Hey Al, thanks for the comment on cable length.  I'll check in to it.
as I interpret various statements in the manual for the PWT its XLR output appears to simply be balanced AES/EBU, presumably 110 ohms.
Andrew, I agree with Al’s statement that the XLR output is the typical AES/EBU 110 ohm signal used in digital devices.

If you want to experiment with sound quality, you can use the AES/EBU output with a passive transformer which will convert the 110 ohm signal to coax’s impedance of 75 ohms. The Canare transformer has received good user reviews...
https://www.bhphotovideo.com/bnh/controller/home?O=&sku=406162&gclid=CjwKEAjw19vABRCY2YmkpO2...=

I believe you will find the coax hook-up to the Chord to provide excellent sound as I did, especially since the PS transport is outputting a bit-perfect signal.
As mentioned, the cable you choose is important. That could be a potential weak link in the system, not the coax input/output.

Andrew, thanks for providing the link to the Stereomojo review. The reference to "S/PDIF via balanced XLR" in the review should most likely have said "S/PDIF encoded via balanced XLR." That would be consistent with what is said in the PWT manual, which also indicates that the XLR output is AES/EBU compatible (as stated in the excerpt you quoted). AES/EBU compatibility necessitates a nominal impedance of 110 ohms, and various other signal characteristics that differ from coaxial S/PDIF. AES/EBU and S/PDIF **encoding** is very similar, the difference being in certain control (non-data) bits. And surely the encoding that is used on the XLR output of the PWT would have been designed to be compatible with the AES/EBU inputs of consumer-oriented DACs.

Also, regarding the following comment that is stated in the review in support of I2S as being the best performing output...
The PWT uses an asynchronous clock that is completely divorced from pulling data off the optical disk when using I22 [sic]. Normal clocks float with the disk’s output and can introduce artifacts.
... while I wouldn’t quite classify this as techno-gibberish, I’ll say that it is not particularly meaningful and shouldn’t be taken too seriously.

Finally, to add clarification to my earlier comment about there being no coax to USB adapters that I am aware of: There are, of course, adapters that can provide many kinds of non-USB devices with a USB interface. However in all such cases that I am aware of those devices enable a non-USB peripheral to communicate with a computer’s USB "host controller," and would not enable a peripheral (i.e., a non-computer, lacking USB host controller functionality) to communicate with another peripheral, such as the USB interface on a DAC.

Good luck. Regards,
-- Al

lowrider57,
On this,
I believe you will find the coax hook-up to the Chord to provide excellent sound as I did, especially since the PS transport is outputting a bit-perfect signal.
As mentioned, the cable you choose is important. That could be a potential weak link in the system, not the coax input/output.
In choosing a cable do you mean choosing something that's exceptionally well shielded with low loss and good connectors?  There are coax cables like this that don't break the bank.  --Or do you mean venturing into more esoterically constructed cables that are high priced?
.....Or maybe you were referring to the proper cable length in your post?
What coax cable do you like?
Regarding the coax cable, I contacted PS Audio and got the following reply.  I'm not including the authors name as I didn't mention I'd use his email in a post.
_________________________

Good morning,

Though a bit expensive, we really like Anti-cables.

Specifically, http://anticables.com/interconnects/digital-rca-interconnects#!/Level-3-2-Reference-Series-RCA-75-Ohm-Digital-Interconnect/p/14696953/category=3682629

Though a bit expensive, this COAX cable is brilliant. The length is less important, and it’s the 75 Ohms which is crucial.

Best,



Well, I’m not sure what to suggest regarding that cable. On the one hand I would of course consider a recommendation provided by PS Audio for a cable to be used with one of their products to be extremely persuasive. On the other hand I don’t see how a cable employing that kind of construction can maintain an accurate 75 ohm impedance, at frequencies extending far into the MHz (radio frequency) region (those frequencies being very important in the transmission of digital audio signals), and without significant variations in the impedance along its length.  Not to mention the lack of shielding.

BTW, I note that Anti-Cables only offers their digital interconnects in a length of 1.5 meters, and near the bottom of their web pages on those cables they reference the paper by Steve Nugent of Empirical Audio which explains the rationale for that length. That length should be viewed, IMO, as providing the best odds of being optimal (unless an extremely short length is practicable, such as 6 or 8 inches or so), but both technical considerations and anecdotal reports that can be found here and elsewhere suggest that it will not always be optimal. As I mentioned earlier what length will be optimal depends on signal risetimes and falltimes (the amount of time it takes for the signal to transition between its lower and higher voltage states, and vice versa), which is almost never specified, and several other component and cable dependent variables.

Good luck. Regards,
-- Al
andrew, much of my knowledge of digital cables was learned from Almarg and others on the forum. My background is in the analogue world of broadcast and studio recording. So digital came later.

It is a trial and error process, so buy from companies that offer a return policy.
I agree with Al's statement regarding the construction of Anticables. We need to hear from a user's experience with them.  
My first coax cable was a 1.5m Mogami for $30, not great, but it got my kit up and running. 
A good explanation of spdif cable...
http://www.positive-feedback.com/Issue14/spdif.htm
Thanks for the comments.  They are very helpful to me.
Thanks for the comments.  They are very helpful to me.