Hi Akoma,
I'm going to be very honest with you right from the bat.
Get your Onkyo TX-SR606 back, and get rid of the Harman Kardon.
I had so many problems with HK in the past, plus I read too many horror stories.
Why did you swap with the HK in the first place?
Your 606 was not satisfying for you?
At the price of the 606 right now, I'll say it is an excellent deal and a fine receiver. And the 607 is only $375 now, not much more than the 606, but the 606 might be better for you, depending on the set of features you are looking for. I bet that you can get the 606 for about $299 right now.
So, make the final swap for the best this time around.
Bob
Note: I'm pretty good at fixing electronics, but I failed with some Harman Kardon receivers.
And if you have to paid someone to fix it, just forget it. Simple advice from me, just stay away from Harman Kardon, pure and simple. But that's just me, and I know a thing or two...