I addressed this issue in another post, but you may not have seen it. Here is info straight from Avid on their FAQ about these units:
I own a Duet/Quartet from Apogee can I get a copy of Pro Tools IO Control so I can control the interface from my Artist Series controllers via EUCON?
Pro Tools IO Control software is only compatible with the black, Avid branded Pro Tools | Duet and Pro Tools | Quartet interfaces and does not work with standalone Apogee interfaces which are supported by Maestro software.
Can I download Windows drivers for my Duet/Quartet Apogee interfaces?
Only the black Avid branded interfaces from the Pro Tools | Duet and Pro Tools | Quartet solutions can utilize the windows drivers. The silver standalone interfaces from Apogee only work with Mac OSX or iOS.
And there is no way to just buy the new interfaces without Protools. If you want to use these this way you would need to:
1. Sell your existing silver one
2. Buy the new units
3. Sell the Protools software activation code that is bundled with the new units.
4. Use the new units with your existing Protools software or with any other Mac or Windows based DAW.
Here is the link to the FAQ:
http://avid.force.com/pkb/articles/FAQ/Duet-Quartet