After relatively few miles, and gentle usage (no loud music, less than 10% of the volume), the dash speaker let stopped working. The speaker system was supposed to be a premium upgraded Harmon Kardon sound system, but a failure from such mild use after 3 years is inexcusable - it seems that a speaker in a smartphone playing at max volume for years is better built. Also, there have been numerous complaints and recalls (TSB's) for the car stereo systems.

When I was originally getting the issue diagnosed, there was the potential that it might have been the head unit which the price cost for replacement is $3.3K (like 10% of the vehicle purchase price). I got lucky in that a new speaker is only $100. I reached out to Subaru and informed them that there are manufacturing defects in their stereo system beyond the models and years listed under their TSB, but I have yet to hear back from them. I understand that sometimes there are quality control issues that can slip through the cracks, but the expected fair use of a product such as an audio device should be more than a few years. There are cars with original speakers that are two decades old that still work.