Longest USB cable length to DAC for audio?

[epping4est]

Although this topic is somewhat old, I just received an email from Simaudio (Montreal) stating that my 16' USB cable is too long for use with their Moon 100D USB DAC:

 

USB audio should never be transmitted over more than 1 meter (3 1/4 feet). Your 16' cable is fine for transmitting data to a printer. But you should never use that with audio equipment.

 

BACKGROUND: The 100D suddenly failed, and I had sent the unit to Simaudio for repair. While waiting for the repair, I decided to purchase Schiit Audio's True Multibit DAC for use with my Jotunheim -- then the Multibit, too, failed suddenly. Not truly knowing the exact cause of the Multibit's death, I further raised the question of "static discharge" via the cable with Simaudio (who still had my unit in their repair shop). The above was their response, as part of their confirmation that static electricity was certainly the culprit.

 

Can anyone confirm the validity of Simaudio's statement?

 

I have myself built products wherein product testing included zapping the device with a rather expensive test tool that generated very high static voltages. The product didn't ship until we had devised adequate shielding and grounding.

 

 

 

[epping4est]

1 hour ago, GregWormald said:

Is there a reason that you don't believe the designer and manufacturer of the MOON equipment?

 

Your question suggests that the manufacture's word is the standard by which the product should be judged. Yet a house built with ladders to the 2nd floor would be rejected on spec. A car built without seatbelts would be rejected on spec. A transmitter generating frequencies outside its nominal range would be rejected on spec. Likewise, a DAC offering a USB2 port that cannot accept a legitimate USB2 cable should be rejected on spec. (At the very least, Simaudio should post a disclaimer on their website: We do not support USB2 cables whose length exceeds 1m.)

 

Here are just a few examples of max-length USB2 audio cables, readily available for purchase:

5m: https://silversonic.com/products/digital-cables/mirage-usb/
15ft: https://www.moon-audio.com/silver-dragon-usb-cable.html

5m: https://www.amazon.ca/AudioQuest-Pearl-8K-10K-48Gbps-16-4ft/dp/B08J5YH328/ref=sr_1_26

 

In its blanket statement, Simaudio says that "USB audio should never be transmitted over more than 1 meter (3 1/4 feet)."

 

Really? There are quite a few posters on this thread alone who violate the above length restriction. How many of those people saw their DACs fried by static discharge from a "too long" cable? Don't know.

 

[epping4est]

In fairness to Simaudio, the 100D was developed for USB1. The USB 1.0/1.1 spec limits the cable length to 3m -- still 3x longer than Simaudio's stated maximum for any USB cable.