32 ohm headphone amplifiers
prices on 58 models— amplifiers for which the minimum headphone impedance allowed is 32 ohms or less.
32 ohms is the most popular impedance rating in consumer (non-professional) low-impedance headphones. This is primarily due to a combination of overall sound purity and modest signal power requirements: the sound quality of such “ears” can be quite high, and for their effective operation, even the built-in amplifier in a smartphone or other similar device is often enough. So it makes sense to use external amplifiers with such headphones not so much for buildup, but to further improve the quality and/or save energy in a portable gadget that plays the role of a player.
For this reason (as well as for some others), not every headphone amplifier provides the ability to work with such low impedances. And given that too low an impedance is fraught with overloads and even damage to electronics — you can connect 32-ohm "ears" only to amplifiers where such a possibility is directly stated — that is, models from this category.