That’s very weird, I didn’t think that was possible 
(It shouldn’t be possible, but I’m guessing that it’s been messed up by the upgrade to Windows 10)
From the deviceinfo file:
These are rge devices that Audacity is trying to use:
Selected recording device: 6 - Entrée ligne (TASCAM US-200)
Selected playback device: 10 - Haut-parleurs (TASCAM US-200)
This is the recording device 6:
Device ID: 6
Device name: Entrée ligne (TASCAM US-200)
Host name: Windows DirectSound
Recording channels: 2
Playback channels: 0
This is playback device 10:
Device ID: 10
Device name: Haut-parleurs (TASCAM US-200)
Host name: Windows WASAPI
Recording channels: 0
Playback channels: 2
Note that the ‘host’ system for the recording device is Windows DirectSound, but the host system for the playback device is Windows WASAPI.
So that kind of explains why it won’t work in duplex mode (‘duplex’ = bi-directions, record in and play out at the same time), because whether the “host” setting in the device toolbar is set to DirectSound, or WASAPI, it will be wrong for either the recording device or the playback device.
What I suggest is that we scrap the current Audacity configuration file, and then try to reset the recording and playback devices to sane settings.
To scrap the configuration file (Audacity must NOT be running):
- Reboot the computer (probably overkill, but can avoid some possible issues)
- go to:
*Users<username>\AppData\Roaming\Audacity* (it’s in a hidden folder)
and find the file:
audacity.cfg
and delete or move and rename it.
Then, ensure that the Tascam is properly connected (You can look in the Windows Sound Control Panel to ensure that it is working correctly)
Then Launch Audacity.
In the device toolbar, the “host” should default to “MME”. If it’s not, then set it to MME.
Then select:
Recording device: Entrée ligne (TASCAM US-200)
Device ID: 1
Device name: Entrée ligne (TASCAM US-200)
Host name: MME
Recording channels: 2
Playback channels: 0
Playback device: Haut-parleurs (TASCAM US-200)
Device ID: 3
Device name: Haut-parleurs (TASCAM US-200)
Host name: MME
Recording channels: 0
Playback channels: 2
Optional: You can check in “Help > Audio Device Info”, scroll down near the bottom and check the selected recording / playbach devices.