Yes, definitely better than the Beta. Though, I feel that way about the Dynahi with all headphones. I had a GS-1 DACT (Dynalo) before, but now only the Dynahi. I'm extrapolating from my experience with the Hi that the TH900 will sound great on the Lo. The GS-1 shared a family resemblance with the Hi and both have enough power for the TH900.
I tried the Anax mod (and other ones) as well. I came to same conclusion as paradoxper and preproman. It improves some things at the expense of others. I ended up reverting back to stock form every time.