So, I've had my A30 Pro setup for 2 days now.
Like others have mentioned, mine does suffer from some coil whine from the internal power supply when the rear rocker switch is on, and the front toggle switch is off (not in any other positions).
However, I would have probably never noticed had I not read about it in this thread. I'm usually up quite early in the morning (around 4am), and it's pretty quiet. Even then the coil whine on my unit is only audible if I get within 8 inches or so. Once my PC is on, or there's more room noise later in the day, then I'd probably need to push my ear up against it to hear anything.
As long as it doesn't get any worse it's not going to bother me.
I'm more concerned about how hot it gets. I might get out my FLIR and post a thermal image once my Hifiman Edition XS arrive, but it was already warmer than I thought it would get with my AKG K701's connected. I'm assuming it's going to be hotter the harder the headphones are to drive.