A while back, while editing a video for YouTube on the Pi 400, the audio began to cut out. This is on the headphone jack built into the Pi 400. It was so bad as to be unusable. At first I thought the software was lagging. After a while, I verified it was a hardware issue by wiggling the jack around. After opening the case up, I discovered that the solder joints on the jack had come loose, as they were very poorly soldered. I was able to bring out the Ryobi cordless soldering iron and had it resoldered in about a minute. The jack is working again, and it does not seem there is any damage to the pads on the PCB. I'm surprised this hadn't failed sooner, judging by how poorly the soldering job had been done. Luckily I have no trouble with such issues, but had this been in the hands of a non hacker type, the outcome would have likely been far more frustrating.
I discovered the dacberry 400s quite recently, and may pick one up at some point, as the audio output on the PIdock 400 is very flat and quiet, and turns off when the display goes to sleep.
So far, the system is still doing well, and I continue to use it as a daily driver for all purposes.