Headphones

The problem with that perception is that there's no linear way to measure improvement in the space as there's no objective way to declare a "better sound". It's not like a cellphone that can claim x16 speed, x10 storage.

Also don't forget we're getting improvements in the space, while entry level headphones have barely improved now have sub 200$ planars, Audeze is doing 300$ gaming headsets, headphones are using newer technologies in their drivers. It is no longer a Sennheiser vs Beyer / Audio Technica, now there's a lot more options.