Here's how to load the Thesycon XMOS driver on Windows 10 and Foobar 1.3.9 ..
I installed the driver from
http://www.xmos.com/support/usb-audio-driver-support on Windows 10 64bit.
I did not have process a signature free process.
I am using the Gustard X20u.
I installed SACD decoder 0.9.6 and ASIO support 2.1.2 on Foobar 1.3.9.
When you install the above driver it creates a C:\Thesycon directory
Go to C:\Thesycon\TUSBAudio_v3.20.0\EvaluationKit\DriverPackages
And execute VAL_KITS_DEMO_DriverSetup_v3.20.0_dbg.exe to load an experimental Thesycon XMOS ASIO driver
Select TUSBAudio ASIO Driver under foo_dsd_asio
The default Theyscon sample rate is 352800hz 24bits with options to change the USB streaming latency, ASIO buffer size and volume.
I can successfully upsample all outputs in Foobar to DSD128 for processing by the X20u.
Presumably the same will be true for the U12 and X12.
Note this is a demo Thesycon driver and beeps every 5 minutes after 60 minutes.
I have since gone back to v2.23 XMOS ASIO driver downloaded from
http://jlsounds.com/drivers.html
The v2.26 download now gives me a security error.