Interesting SPDIF vs. USB interface FIndings

[John R.]

I do not doubt John Kennys findings at all, but with my MSB and two different Naim DACs the stronger SPDIF output sounded better. As I said in my post above, one can never generalize something, one should find the optimum way for ones particular setup.

[The Computer Audiophile]

I have got a MSB Anlalog DAC/Power Base with Quad USB and SPDIF input and I think that one needs to take a lot of things into consideration when comparing both inputs. Otherwise a comparison is useless. I use a Macbook Pro (older model) with the newest OSX (stripped down), HQ Player and a Wireworld Platinum USB 7 cable into my MSB Analog DAC for streaming and a PS Audio Perfect Wave transport with a Naim Audio DC 1 SPDIF cable for spinning my CDs and both ways the sound quality is very good. However I slightly prefer the streaming route soundwise.

 

I tried Audirvana, Pure Music and HQ Player and I prefer HQ Player in its purest form (no digital filter, no dither/no noise shaper, no sample rate conversion and of course no PCM to DSD conversion) since this way it sounds the best to my ears. Trying out all this different software players I came to the conclusion that all of them sound different although all of them passed the bit perfect test and were compared using them in the most neutral form regarding settings and in the form with the settings I liked the most. It makes even a big difference whether Wifi/WLAN is on or off with the MAC. Taking all this into account my personal oppinion is that one should not generalize things like saying USB is better than SPDIF or the other way around.

 

The very same goes for SPDIF. Every SPDIF cable has got its own sonic signature, every CD transport has a different sound and even the power cable for the CD transport ends up changing the sound of the very same transport.

 

Now one might say that the PS AUDIO Perfect Wave transport is not a normal transport since it rips the disc, stores it into a large buffer (64 MB as far as I know) before it outputs the data, but the same above mentioned findings are valid for my heavilly modded Naim Audio CD transport with a swing arm CD transport, too. This transport has got two SPDIF outputs only differing in signal level. One is 2 Volts peak to peak and the other is 4 Volts (well above the standard) and guess what? The stronger one sounds so much better with a variety of DACs that make me wonder why most SPDIF outputs are only 2 Volts.

 

As you can see I tried a lot of things and my conclusion is that one can easily compare apples to oranges although one thinks that he compares apples to apples. My advice is that one should optimze the USB route starting at the PC/Mac and to optimze the SPDIF route and than decide which one to prefer. But in my oppinion this is only valid for this particular set up and that these findings can never ever be generalized.

Hi John - Thanks for all the details!

[Sam Lord]

Let me second Chris's sentiment: excellent statement by John R.

 

I want to know which measures better. Was Gordon Rankin and every reviewer wrong when asynchronous (meaning synchronous-with-receiver) USB Audio arrived? Is a strong but distant clock better than a clock right by the DAC?

 

Countless builders said and say that the best-performing DAC requires an excellent, *close* clock. SPDIF will never satisfy those criteria. But a number of others like Mike Moffatt and John Stronczer have consistently and persuasively disagreed with the notion that asynchronous USB is the better method. SPDIF with WC output has nearly the same clock and buffering noise generation as USB. As always he answer varies with implementation, but in measured performance one circuit will generally win.

 

If SPDIF is better, let's abandon USB and move on. Please, would some builder publish some data so we can end this argument? After all, eliminating the clock next to the DAC *altogether* would surely lower noise.

[juanitox]

this morning , i have heard a friend system with multi-amplified horn speaker and a simple old cd player and Wadia X32dac and it sounds nearly as good as my system with computer audio ( roon/tidal .hqplayer micro-rendu ; T+A dac8DSD) go figure..

if all this computer audio sophistication was just an illusion !? in the meantime it keeps us busy

[monteverdi]

That article on DAR Gordon Rankin on why USB audio quality varies | DAR__KO is quite interesting and explains to some extend why USB as implemented presently for audio is error prone with no error correction scheme (same as SPDIF). Maybe the error rate both in time and bits is lower in good implemented SPDIF (or AES/EBU)?

A printer works quite error free as the bit packets are corrected. So may be the concept of USB DACs as presently implemented which is just a derivative of the SPDIF idea what is faulty. Just like a printer there should be a significant memory in which the data are correctly transferred to and used as the DAC and its clock requires i.e. a DAC with built in server. I listened at this year's Highend to the Totaldac D1 integral-headphone music server/DAC and was quite impressed!

[Barry in Calgary]

Hi All

 

The new MSB Quad USB module arrived a few days ago, installation was trivial, and I started comparing SPDIF and USB performance after about 10 hrs. of module break-in (no break-in required according to MSB) on 14/44 and 24/192 files.

 

The difference between SPDIF and USB is now extremely hard to detect. It is there, but not significant (far less than the difference between two well made USB cables). I prefer SPDIF, but either is waaay better than the original MSB USB module.

 

The SPDIF source is the Oppo 105 used as a media server, which while okay is not in the same League as an Aurender N10 or Bryston BDP-2 which both have nice Coax implementations and from what I gather less noise than the Oppo (which continues to amaze me).

 

I'll do more comparisons in the next few day letting the module acclimatize before and after I upgrade the firmware on my Intona Isolator (Just received the Intona firmware field updater). By the way, I'm also using an Uptone Regen power by an SBooster LPS in my USB chain and 2 Curious cable links and Light speed harmonic cables, so hopefully I'm doing all I can to give USB a fair shake.

 

After that, I'll see if I can borrow a BDP-2 or a Linn player/DAC from a local dealer and compare USB against dedicated players which output SPDIF through BNC or RCA connections.

 

Anyway, very satisfied with the Quad speed module. Well worth the additional cost.

 

Regards

Barry