I was looking for some simple headphone amplifiers for translation booths, to give the translators the ability to adjust the volume of their headphones. No need for super Hi-Fi quality in a relatively noisy place, but they should be of sturdy quality.
My expectation was to find some gadgets below $20,- but it turns out that there's hardly anything on the market below $60,- (besides unassembled do-it-yourself kits).
This seems crazy since a headphone amp is already built into almost every gadget that can produce audio. Looking at USB audio interfaces, these do drop under $40,- and could also do what I want, but it still feels like an overkill.
Would it hurt the original amplifier if I adjust the volume to an excessive level and simply solder a stereo resistor between some jack-plugs?