Народ, как там со временем загрузки и возможностью установки Viper4android?
Viper4Android/the hole audiofx engine works fine with adapted config file, I've sent sntron the modification, may be they put it in the new firmware. I don't know if i got the right email adress because I don't get any replys...
For People willing to get Google Voice work out of the box:
The Cusp Unit comes with a WM8988l(
https://www.wolfsonmicro.com/documents/uploads/data_sheets/en/WM8988.pdf) Codec chip. The chineese however did not connect a microphone to Input2 of that chip. I really don't know why, may be they forget it

As you can see, no connection, but the android 4.4.2 alsa driver switchs to that input when Google Voice is fired.
As the internal microphone booster is deactivated, one can connect a preamplified microfone to LInput2 RInput2 of that chip.
Here are three examples of Mic amplification for the WM8988(exp. from android tablets):
3rd example gives best Audio quality.
Only tricky thing is soldering the Inputs to the chip because it is only 4x4mm.
Good Luck!