I’ve recently bought a new Lenovo Yoga Laptop 300, 11’, N3710, fanless, SSD (dead silent), 1G LAN.
The problem is when Lenovo turning back ON (from reboot or power off), it’s (kind of) HANGs the PWD’s USB device (XMOS not responding anymore), and PWD needs to be restarted (to be recognized by any PC).
After some investigation, I’ve found out that after turning off the laptop, USB device (inside the Lenovo) switches OFF (Red LED in PWD), but after a few seconds switches back ON (Green LED in PWD).
The simple solution is to disconnect the USB cable before pressing the power (ON) button, and then connecting it back (until the next power on).
Any ideas ?
Wow, so many solutions here … 
Nevertheless, I have one - Belkin USB 4-Port Ultra-Slim Travel Hub.
What would an unpowered usb hub do?
I would think unplugging is the simplest solution. I usually put my music only laptop to sleep, rather than off. But my Benchmark doesn’t have any problems on or off.
What about switching the dac to a different source before powering down the laptop? What does that do?
Yes, unplugging the USB would be the simplest solution, in the sense that there is no added hardware. Valery is looking for the simplest solution in terms of ease of use - a concept with which I agree. Once the USB hub is installed, then the system is simply used when and as desired with no magic dance needed in order for everything to work.
I suspect that the powered hub corrects this issue by not cycling the USB B+ coming into the PWD USB input. Perhaps a more audiophile solution would be to use a Schiit Wyrd, or Regen or some similar USB reclocker instead of the powered hub, since these would also likely improve the sound quality as they are intended to do.
J.P.
JP, the hub Valery posted is not powered, it only gives you 3 extra usb ports.
I still would like to know if changing inputs does anything.
You may be right about adding a Regen or a LANRover, but that is an added expense.
Doh!!! Yes, I missed that detail.
Maybe helps because it is USB 2, or just the additional translator stage between the DAC and the laptop? Perhaps the hub is storing enough energy that the DAC does not see the USB power line cycle since the laptop USB only powers down for a couple of seconds?
Curious…
J.P.
The Belkin Hub apparently preventing [filtering ?] from the laptops USB (Hub) to send a signal [impulse or whatever] during Power On, that hanging the DAC XMOS.