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USB sucks

USB really isn‘t the right connection between DAC and Server: depending on cables used, you get very different sound quality if the server manages to recognise the DAC at all. Some time ago I replaced my highly tuned Mac Mini (by now-defunct Mach2mini, running Puremusic via USB) with an Innuos Zenith Mk3. For starters I couldn‘t get the DAC (Antelope Zodiac Gold) and server to recognise each other, transmission from the server under USB2.0 wasn‘t possible because the server is Linux based (mind, both alledgedly support the USB2.0 standard) and when I finally got them to talk to each other (by using Artisansilvercables (pure silver) the sound quality was ho-hum. While I understand the conceptual attraction to have the master clock near the converter under asynchronous USB, the connection‘s vagaries (need for exact 90 Ohms impedance, proneness to IFR interference, need to properly shield the 5v power line, short cable runs) makes one wonder, why one wouldn‘t do better to update I2S or S/PDIF or at the higher end use AES/EBU. After more than 20 years of digital playback, the wide variety of outcomes from minor changes seems unacceptable.

Since then and after a lot of playing around I have replaced the silver cables by Uptone USPCB rigid connectors, inserted an Intona Isolator 2.0 and Schiit EITR converting USB to S/PDIF. Connection to the DAC is via Acoustic Revive DSIX powered by a Kingrex LPS.

The amount of back and forth to make all this work is mindboggling, depending on choice of USB cables (with and without separate 5V connection, short, thick and God-knows what else) is hard to believe for something called a standard interface and the differences in sound quality make any review of USB products arbitrary verging on meaningless.

Obviously S/PDIF gives you no native PCM or DSD but, hey, most recordings still are redbook, anyway.
Conversely it is plug and play although quality of the cable still matters but finally it got me the sound quality I was looking for. It may not be the future but nor should USB, given all the shortcomings. Why is the industry promoting a standard that clearly isn‘t fit for purpose?

Finally, I invite the Bits-are-bits naysayers to go on a similar journey, it just might prove to be educational.
antigrunge2
antigrunge2 OP
1,461 posts
 
@dougeyjones,

as you are so assertive on your view: why is there a significant market for USB clean up and reclocking devices by Uptone, Intona,IFi, Schiit, Berkeley Alpha, InnuOs, Aqua, DCS et al?Are they all selling snake oil? Or are they maybe onto something after all?
Listen and enjoy
jaytor's avatar
jaytor
766 posts
 
Of the various inputs supported by DACs on the market today (SPDIF, AES3, Optical, I2S, USB, Ethernet), only USB and Ethernet provide an asynchronous input.

Using an interface that requires the clock signal to be generated by an eternal device (server, streamer, reclocker, etc.) and then pass that over a cable with connectors (which even in the best case will have impedance irregularities causing reflections) makes no sense with today's technology. The DAC needs to be responsible for the clock in order to minimize jitter. 

Ethernet might ultimately be a better electrical interface than USB, but until the industry standardizes on a single, simple protocol over Ethernet, USB is our best option. 

I'm sure there are otherwise good DACs that don't do a very good job with USB, but that is changing. With the rapid increase in popularity of streaming, most DAC vendors are recognizing the importance of USB as an interface, and I think it won't be long before this is the preferred interface for most users.
dougeyjones's avatar
dougeyjones
163 posts
 
@Antigrunge

I’m assertive in my opinion because it’s borne out by evidence derived from testing. The reclocking and cleaning products you refer to have been shown to do more harm than good on numerous occasions if you’re referring to USB.

Example:

https://www.audiosciencereview.com/forum/index.php?threads/ifi-micro-iusb3-0-usb-filter-review.11284...

The conclusion really says it all.
djones51
4,947 posts
 
The market for USB clean up devices is there because people still believe USB is a problem interface from when adaptive or isynchronous transfer was used. Most all modern competent engineered DACs don’t use the clock sent any longer so what difference does it make how many times you reclock the signal before the DAC? Line noise isn’t a problem as the USB buffer in the DAC isolates it and it’s the firmware or software that translates the signal that interfaces with the DAC chip not the incoming line signal. Actually SPDIF will have more jitter than USB since it uses the clock from the source sent over the wire. As with anything that's product specific some DACs do better jobs. 
fsonicsmith's avatar
fsonicsmith
967 posts
 
Gordon Rankin of Wavelength Audio, especially now that Charley Hansen is gone, is widely acknowledged to be among the world's foremost experts on digital conversion. The Doctor Anthony Fauci of digital. Gordon says that USB is the only way to go. His DAC's are both expensive and rather simple looking and I don't recall every seeing any explanation as to the converter chips he uses or his circuit topology. But I digress. I don't pretend to understand.the ins and outs of any particular type of connection, but I will stick with USB.
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