From your earlier post it appears the problem was with the soldering of the DSP Codec onto the board. So either they had to replace the Codec and didn't do a good do soldering it back on the board or there was an additional failure to the solder joints.

I'm guessing that replacing the Codec is very difficult and requires specialized equipment. (e.g. Selective IR reflow) So some pin may have gotten a little less solder an didn't make a good connection. Shipping vibe may have caused it to fail hard.

It's also possible that the solder joint failed independently of the rework. Solder joints do fail over time due to thermal shock, migration, etc.

My 2 cents...

FWIW, my 975 had similar crackling noise problems. I sent it back to Outlaw and it was diagnosed as a faulty hdmi board. I was charged a fair price for its repair and shipping back. The returned unit, didn't work as well as the one I shipped back. The crackling noise was still there and the HDMI ARC no longer worked. I documented the noise with sound recording clips using various inputs and from my headphones. Outlaw was great and asked me to ship it back on their dime. They said the problem was the main board and said they replaced it at no charge and shipped it back. This repair cured the crackling noise but I was suddenly having hdmi audio problems. I tried a HDMI reset and eventually a unit reset, eventually the entire unit bricked (no audio output from any input including the tuner and analog).

Outlaw had me send it back on their dime again. This time they basically said it couldn't be repaired. They were great and refunded the amount I spent on repairs and shipping (except for the original shipment back to them). I ended up getting a 976.