The new BA in my opinion is really up there against all ToTL, with the switches, basically all range are covered. They are something in between their witch girl and music box line, sounds are more refine with bigger soundstage, though it is not a reference pair.
As for the A100, definitely one of the most complete amp in the market, basically it can drive most iem or even cans very well, like putting regular Dac on steroids even at low gain. It widen the soundstage quite a bit, the background is pretty dark too. Only drawback is it doesn’t have digital in.