Back to the original question... Try
this page on AVS forum regarding the popping.
"Thank you for the inquiry. The popping that has intermittently
occurred might have been a result of a loss of sync with the HDMI
connection to your source device. When shutting the AVR down, the
popping is eliminated due to the devices (AVR and whichever source
you're listening to) executing the "handshake" that is completed by
devices that are connected via HDMI. If the popping occurs again,
please try shutting off the source device instead of the AVR to see if
the popping is remedied. I hope this is helpful. Please let me know if
the problem persists."
I'm afraid it's not good news as I've seen many reports of this in online forums re: HK (247 and 347) and I have a good friend who went through an absolute nightmare with HK on his 247. They promised that a firmware upgrade would fix this problem (and a few others) and after many failed attempts he finally mailed it to them for analysis. They received it and told him that they'd send him a new one within ~6 weeks. (can you believe this!?)
At this point, I told him to raise a huge stink with them and they revised the time down to 3 weeks, but still, an awful experience to be without your HT hub for so long. They ended up upgrading him to a brand new more expensive AVR as a result, but when he got it, it still doesn't pass 1080p/24 and has a few other bugs he just can't work out.
I realize this is a bit of a downer post, but when I hear about such awful customer service I feel like I have to do my part to spread the word when there are great companies like Axiom out there who really do try to do right by their customers...
It sounds like thus far you've had a better experience, my advice based on my friend's experience is to stay on HK until you get it fully resolved and you're happy. Maybe you can even work an upgrade out of the deal. It sounds like they're working out of their "firmware funk," so hopefully you're timing it right to be near the end of the problems.
Good luck!
Jason
