Need to under stand Asynchronous USB


So I just got a Marantz ND 8006 Network CD player. Im using it as a network player and CD transport  and I output digital to my NAD M51 DAC. I’m using my IPad to stream TIDAL and that works tip top. However, it’s the USB inputs that concern me. I have a choice of a front connection and a rear USB DAC connection. 

Couple questions:

1. The USB DAC input is for a Mac or PC hook up, but is there any other way to use an input like this?  Does it have to come from a computer or can a USB hard drive work with an input like this?
2. More importantly the front USB input is NOT asynchronous.  I think they make a reclocker I can put in between the USB and the unit. My question is do they make a USB hard drive with a built in reclocker with a good amount of hard drive space?

this is all new to me, so any help would be appreciated. 
last_lemming
Last follow up, trying to improve the USB stick input on the Marantz would be sketchy. It’s going to be one of those USB 1.0 devices like on a cheap blu-ray player, and you’re still connecting to the M51 via coax anyways.

I mean, you’re using the Marantz as a pass-through atm (effectively you’re using it as SPDIF output), for which I see no real benefit apart from when its playing CDs (which you could rip and either play directly to the NAD or stream via the Marantz).

I see the 8006 has ethernet and wifi inputs and USB output, so on paper, the best layout would be:
1. files on network storage (computer / laptop / big USB drive / NAS)
2. ethernet or wifi to Marantz
3. Marantz USB out to M51 USB in -- here is where you may want to try a USB reclocking doohickey OR
3.1 Marantz USB out to M51 AES in (like my Yellowtec PUC2 Lite / Berkeley Alpha USB, e.g. USB-SPDIF/AES converter) OR
4. Marantz SPDIF out to M51 SPDIF in -- there are still some SPDIF reclocking doohickeys

Where this could get very silly is a config like (just picking products at random)
Marantz USB out > Uptone Audio USB Regen > Yellowtec PUC2 Lite > M51 AES in --we’ve all tried this kind of thing, though! It’s probably why a lot of manufacturers have more and more all-in-one network players like your Marantz, or separate network transports, even combo network streamer-DAC-preamps. So many damned cables and power supplies. And DC umbilicals and power cables to sell for them!
How much quality is lost streaming Tidal via wireless vs hardwired?  I read that wireless is not so good. 
It depends on the device. The old squeezebox touch's digital out was better wired vs wifi, but times have moved on, e.g. with the new Auralic stuff, wifi is reported to be equal if not preferred. You can just try comparing the two on your Marantz.
So I use tidal through my iPad to control the Marantz streaming. The Marantz is connected to my WiFi, so is the actual music data coming from my iPad or my computer in my room where the WiFi is located even though I have no app downloaded on my computer ?
...the Marantz is doing the playback; the iPad is just a remote control; your wifi network contains all the data being sent to and from the Tidal servers