Need to under stand Asynchronous USB

Item 2) you mention, does that mean my DAC does the reclocking and I don’t need an external reclocker?

I have the M51. The USB - the type B - input is async from XMOS. The DAC uses its own clocks. However, it’s been widely agreed from reviews and users (and I concur, also) USB is not the best input for it rather than AES. I tried various USB decrappifiers from iFi and linear power supplies, as well as various coaxes but they didn’t swing that judgment.

I use a Yellowtec PUC2 Lite which is a USB-AES converter and that’s the best sound I get from the M51. Sound is muscular and detailed.

It seems to take a great deal of extraneous gear for USB to perform optimally (reclockers, isolators, power supplies, e.g. SOTM or Uptone kind of thing), by which point you could have gotten a better DAC period!

The other USB - type A - input you’re talking about implies using a USB flash drive for local playback. That’s not what the other USB jack is for - rather it’s for updating the firmware (1.39 is best for the M51 rev1!)

If you want to use a computer and/or network storage as a front-end, then you might want to look at a streamer (e.g. Bluesound, Auralic) with any kind of digital output. It can be USB, optical, coax, even HDMI, or AES, but as I said, the M51 likes AES the best. Or indeed track down a Yellowtec PUC2 lite + USB streamer.

Moto. I’m feeding the DAC info through the Marantz.

I guess im still a little confused. I’m runner no a standard thumb drive into the Marantz witch then sends it via coax digital out to the coax in of the DAC (nad m51).

Do I still need a reclocker or something?

Either USB input will have equivalent performance.

Asynchronous USB refers to the DAC being the conductor in the communication. The PC/Mac software or whatever doles out data as the DAC requests it. So, it’s a cooperative arrangement. The PC/Mac picks what to play, reads it and sends it down to the DAC, but the DAC remains in control of the metronome.

The front USB connection is for media devices, including a hard drive. Since the Marantz is also acting as the player software, the idea of asynchronous is kind of irrelevant.

In both cases the DAC will be in charge of the metronome.

Now, if you use S/PDIF via optical or coax this no longer happens. Then the source device owns the clock, and the DAC better keep up.

Oh I get you now, @last_lemming . The Marantz is feeding the contents of your USB drive via coax to the NAD. Like Erik said, for coax, the clock is embedded in the SPDIF data stream from the Marantz. Here the source is the clock master and this signal is synchronous. Folks used to sell SPDIF reclocking devices on the principle that the clocks in most original SPDIF sources (e.g. your Marantz) were bad (i.e. causing high jitter) and the doohickey reclocker would be better....

Now, you could stick the same files on a laptop and plug the laptop into the NAD’s USB input, but this time it’s async cause the DAC controls the clock. Despite this improvement, folks still try to improve the quality of USB sources with new doohickeys (that I mentioned in previous post) on the basis that computers have a lot of electrical noise that come into the DAC.

This is an old article from wavelength but still explains the concept of async USB http://www.usbdacs.com/Concept/Concept.html

You can also read product briefs on things like the iFi iUSB3, Uptone USB Regen. Folks have also now moved to Network sources and transmission devices like your Marantz all-in-one, Auralic G1, SotM, DCS Network Bridge, etc.

I don’t think you need a relocker in either case cause of pitiful diminishing returns! Expect strong rebuttals from those hawking the doohickeys! Note I’m not saying none of these devices can improve the sound, I’m saying they’re usually expensive to the point of (all added up) where you could get a much better DAC / room treatment / Scotch / beer money.