HDX vs. UServe - via nDAC and via NDX; are we failing by the source components?
Posted by: aysil on 09 April 2011
NDX is out, and there is a lot of excitement around its sound and different comparisons with similar devices, with nDAC, different PS, etc. Are we thereby overlooking another important question – the importance of the source component?
Part one: different source components via nDAC
When I had, in an earlier post, reported big sound quality differences between HDX and UServe through my earlier DAC, some members asked if I hear the same differences through my nDAC. Some suggested the differences would diminish through nDAC. I was also very curious.
One by one, I connected HDX and UServe to the same input of nDAC with the same digital cable and listened to different kinds of music from the rips I had made to the on-board hard drives of both devices. (Both are non-ssd versions) The results were identical to my previous findings using my previous dac: “UnitiServe sounds more nervous, a bit more rough, and the micro-dynamics more flat (in comparison to HDX). The HDX has a more relaxed presentation, more resolved, better flow, and more precise rhythm.” I can add further: HDX has deeper soundstage and more correct tone colors.
I don’t know why some members on this forum did not hear the difference in their own system. (It is not a negligible one. My friend accompanying me during the auditioning did not even believe we were playing the same track!) Of course, in a more revealing system the differences would be augmented. My Kondo Souga amp is definitely an extremely revealing amp; annoyingly revealing at times! I hear the different positioning angles of microphones, and thereby sometimes “see” a distorted soundstage or a bent forward piano or things like that. However, any system from the different Naim ranges would also have, to varying degrees, the resolution to convey this kind of differences. (Edit: it turned out later in this thread that those members who have compared these two devices had used a NAS and they were playing the same file on the NAS, contrary to my case. See later on this thread)
I am not writing these to discredit UServe. Its weaknesses are only in comparison to HDX. UServe is probably one of the best sources in its own price category. I wish I could compare it to CD5XS, which is almost the same price. I asked our distributor, but it was not in stock at that time. The only thing I could find at hand for comparison was a less than £1k CD player from a neighbor. It was definitely much worse. Compared to UServe, it had much less detail, and a blurred and muddy presentation.
CONCLUSION 1:
Naim DAC’s “buffering/re-clocking architecture” is Naim’s ingenious solution for the task of GETTING THE BEST OUT OF A DIGITAL SOURCE. It is by no means there to disguise the quality differences of source components, nor does it make up for the weaknesses of inferior sources! Unfortunately, we just cannot escape the issue of the quality of the source component.
Part two: different source components via NDX
What happens when NDX comes into the picture and we use UPnP streaming instead of the S/PDIF connection? Does the characteristic of the source component play as important a role? (With source component, I mean the component which comes before the NDX, for reasons I will explain below) There are already some test reports online, which compare different source components connected to Linn DS devices and describe the differences. In fact, in one of them, HDX scores much better than RipNAS, for example. I wanted to reach my own conclusions. Taking HDX and UServe as two examples of different computer audio source components, I connected both to the modem with the same length, brand of CAT6 cable and auditioned them through the UPnP input of NDX.
First, they both sound quite different through UPnP. UPnP transfer and S/PDIF transfer have very different sound characteristics. I don’t have a clear winner yet; they have different strengths and weaknesses. (This should be the topic of another post.) However, the difference between HDX and UServe remains! In fact, the difference is much bigger because UPnP is the more detailed (and revealing) method of digital transfer. The characteristics of the two source components are exactly the same as above in the previous comparison. It can be quite disappointing to switch from HDX to UServe. The beautiful silky textures of string instruments from HDX give way to a somewhat scratchy presentation from UServe, and the nicely swinging body of the clarinetist from HDX gives way to a somewhat more stiff musician body from UServe.
I must say again: these remarks should not discredit UServe for those who are enjoying this device in their Uniti systems. The description is only relative to HDX, and in regard to HDD versions. The only conclusion to draw is that different computer sources may sound significantly different. (HDX and UServe are, in principle, dedicated computers.)
One interesting note: the difference was consistent whichever server I used to stream the data, HDX server, UServe server, or Asset server on my laptop. That means, for example: when I used the UServe as server, the sound was better streaming data from HDX’ hard disk drive than streaming data from its own hard disk drive. (Edit: this actually coincides with the experience of some members who have compared the devices when playing the same file from the same location and did not find a major difference. See later on this thread)
I cannot know to what extent the above-described differences btw the two devices stem from the actual ripping and to what extent they occur during the process of reading the data from the drives. Many would assume that if the ripping engine and algorithms of the HDX and UnitiServe are the same, the data on the drives should be the same. However, I don’t want to rule out the effect of the different cd-drives of these devices on the supposedly same ripping engines. One interesting test would be to change the save location of the rips and save the rips of both devices to a common third location on the network. (I don’t have a NAS, so this could be a folder in my laptop computer.) I will try to do this test during the next weeks and report to you. It will be interesting to see if the rips from these two devices will sound different when saved to the same third location, and the sonic differences between these rips and the rips saved directly onto the on-board drives.
CONCLUSION 2:
During the online chat on NDX, Gary Crocker called the NDX a “source component”. I doubt if this is the correct term. The digital audio data is processed in the inner topology of a computer source before being transferred to NDX. Therefore, we should call NDX, like other “renderers,” an intermediary component, where the computer IS the source component.
If two computer sources from the same manufacturer can sound so different, I guess different computers, different NAS, even different usb sticks sound considerably different. In fact, I start to believe that, with regard to computer audio, we are in a similar phase to the early 1980’s with regard to cd-playback, when most people believed cd-transports have no influence on sound quality, as “they were merely transferring the ones and zeros to the dac”!
We will soon find out, how the power supply of our computer, or the material of the outer case, or the brand of the hard drive, or the quality of the inner cabling, or any element of the topology of our computer, or even the CAT cable we use to connect to the network influences the sound. When I search back on this forum, I actually find many posts that point at such influences. They have not been the focus of attention of the majority. As the quality of the “renderer” components rise, such aspects will become more audible.
There are some members on this forum, like Tog, who regularly advise that any worry about the influence of a factor on the sound would make sense only if it makes a considerable impact in the current level of the whole set-up, and that we should be able to sit back and simply enjoy the music! I find such warnings very valuable, because audiophiles do tend to forget this basic fact and get lost in worries and details. However, we cannot escape such worries altogether as it is this quest for better sound that brings us together in this forum. Total piece of the mind exists only in Heaven!
Ihau,
Thank you for explanations. They are a delight to read! However, I am not sure if they help here to find the explanation to what I am hearing. The popular science level of knowledge on the "working principle" of computers may not give the clue to what we are discussing here. Those things are usually in the details of the technical implementation of those basic principles. Yes, I trust computers (even more so after your reassuring words 
) - thanks to all the error correction mechanisms and algorithms they incorporate.
When I talked about the judge, I was referring to all those remarks who decide what I "should" be and what I "should not" be hearing!
Aysil,
If you have some time have a look here:
http://www.cicsmemoryplayer.com/
This is a project for building an audio centered PC player.
It makes fascinating reading. Everything from cutting down XP to the minimum, to the honing of the hardware.
In this CICS has even MINIMISED the amount of RAM he uses, as he finds it sounds better.
M
Hey, thank you for bringing this site to my attention. It is actually a detailed technical description of why different computer sources DOES sound different. They even talk about the effect of error correction and how this effects the system overheads. Apparently, I am not the only person talking "rubbish" in this world! 
Aysil,
No.
There is a fascinating journey here ..but ultimately I decided I wanted to spend more of my time listening to music, but I'll watch your posts with interest!
M
And wow! If you are writing to compare nDAC with NDX on this forum, you can act very loosely and nobody will question your intent. If you want to compare UServe with HDX, you need a "testing protocol". I didn't know that this forum has such restricted zones!
BUT, if we were all to try writing our observations up in a properly defined, formatted and delineated way we'd all need a LOT of space.
Do you think we should submit an abstract before being allowed to start a new thread?
M