1) Overbuilt HEA products. Throwing big transformers into a chassis with sensitive audio signal carrying parts makes zero sense. Then lol the designers decided they had to shield their parts from the field effects, creating further sonic problems. If you have to create a shield that means you have field problems in your design.
2) Complicated crossovers. If you have to make complicated crossovers that means you have poorly designed your cabinets and drivers.
3) Dampening your room kills part of the music you are trying to hear. Tune your room don’t kill your music.
4) Conditioning your AC. Adding parts to your AC chain doesn’t magically clean up your AC, it dampens your audio signal.
5) Banana plugs. Adding mass means lowering signal response. So simple yet so many don’t get the basics.
6) Products with multiple inputs. Build two of the same product, one with multiple inputs and the same one with only one input. Be prepared to fall out of your seat.
7) Why do you have equipment racks directly in front of you in the middle of the sound stage?
8) Only a volume control, really? If you only have "A" volume control, you have almost no control over your recorded music. No two recordings are the same, nor rooms, nor ears nor.....
9) Speaker grill cothes. Anything between you and the drivers is something between you and the music.
and 10) Breakin time. It’s all a big joke manufacturers telling you that your product is going to breakin before your demo time is up. Audio parts never stop breaking in. Most barely get started till after a year of constant play.
My list is a little different from "quirks" more of a reality check on obvious issues that this hobby has created and continues to take the shallow way out instead of diving into the deep end and learning how to swim.
Michael Green