Actually just spotted on the website that it is the USB versions that bus power, not the TB versions..
Whilst I am here though, the Clarett is a great, great interface. Mine is use every day and has been used for recording bass on some pro releases. rock solid, dead easy to use and the low latency figures are bonkers good. Love it. I also love the free plug ins that come with the interfaces too including Addictive Keys, which I use every day.