I asked Beyerdynamic throu email. Can A20 work with my future t1v2? Because i would not have money for A2. Answer was - Beyerdynamic A20 can reveal Full potential of Beyerdynamic T1 2nd Generation, And it pair very well with my Dt990 was said...
Did you expect anything else? Did you expect them to say their premium headphone amp would not work well with their premium headphone?
I had an opportunity to listen to the T1g2 with the A20 and with the Woo WA8 portable. I though the T1 was much better with the Woo. The bass was a little bit cleaner, and the highs were more detailed and present.
The point is, you have to try amps with your source and your headphones. Vendors will almost always agree that a combination of their equipment will work and sound wonderful (within reason), and third party vendors will almost always tell you how their product will work and sound better.