The URI A4 overdrives 2 T5s (apparently it cannot overdrive 4, at least according to Dan from SC). I have one which drives two URI superactinic T5s as supplement and it is phenomenal. The A4 plus is supposed to be able to overdrive 4 T5s just like the 660.
Thanks for the ballast information.
Still looking for ballast that's local.
Thanks,
Rj