This actually seems to be a common issue with most modern DACs and it has to do with how they handle audio streams and going to sleep when there is no signal.
When using the ASIO driver, there is a hidden setting in the driver that you can enable, which prevents sleep and is known as always-on...
I would love to see an integrated DAC + Headphone AMP combo based on the AKM4499 chip.
It should be similar to the ZD3:
inputs:
USB
Optical
HDMI
Bluetooth
Coax
outputs:
back:
XLR balanced
RCA
front:
3.5mm SE
4.4mm balanced
6.3mm
Similar to the ZD3, it should support swappable op amps...