There's nothing wrong with your mixer, and there is currently no internal option for the T1 as the configuration of the audio outputs don't allow you to bypass the channel hardware, meaning you can't send a master output past the channels which could be mapped to the software mixer. Any changes made on the hardware would also affect the audio passing through those channels. Unfortunately because the audio is processed prior to being sent to the mixer's channel, there is no ability for a "post-fader" effect as cutting the channel fader also cuts the echo. Sorry!
If there are any changes to this in future, we'll be sure to let you know.