[PROBLEM] DAC does not sleep due to moOde player

[smokey_mountain]

Good time of day, 
First post here, I have been beyond impressed with moOde player on my RPI 4+, fantastic sound, beautiful UX. However, I purchased Topping E70 Velvet to be able to utilize the same DAC for Hi-Fi and TV(optical). USB is connected to RPI with latest moOde player. 

Topping is switched to the mode when no signal is received from the streamer it sleeps within 1 min. DAC does sleep on Optical input when TV turns off but it will not on USB. If I unplug USB from my RPI it sleeps in 60 secs. 

Topping told me that this is not their issue, and that I need to seek help from moOde folks. 

I need DAC to sleep to be able to turn off an amplifier via 12V trigger. 

Appreciate the help!

[Tim Curtis]

Are u using MPD or one of the renderers (Airplay, etc) for playback?

[smokey_mountain]

Are u using MPD or one of the renderers (Airplay, etc) for playback?

Using MPD, DAC is connected via USB straight into RPI 4 USB port, no USB hubs.

[Tim Curtis]

MPD closes the audio output when a track or stream ends and so no bits would be on the audio interface.

The challenge with your issue is how to reproduce it on our end for troubleshooting. My USB DAC doesn't have a sleep mode feature.

[DRONE7]

Which USB port are you using?
If the USB3 then try the USB2 and vice versa to rule out a 'handshake issue'

[smokey_mountain]

Which USB port are you using?
If the USB3 then try the USB2 and vice versa to rule out a 'handshake issue'

Thank you, what I am hearing from other Topping owners apparently Topping DAC only senses 5V rail on USB. I have tried USB 3 and USB 2, no luck there. 
Regardless, moOde is a phenomenal product, thank you for making it possible! Much appreciated and donation will follow.

[DRONE7]

Interesting...so if other users find the 5v rail controls the sleep function then the absence of the 5v causes the Topping to sleep ?
So a switch in the 5v supply would do this ?
Perhaps a split power and signal like the one below with a switch on the 5v may work ?
https://www.tnt-audio.com/clinica/221_diy_usb_e.html