I've had an (unfounded) thought that perhaps, current-out (i.e. very high output impedance, current source) amps could increase isolation in open-back isodynamic headphones by "stabilising" the membrane, counteracting EMF created by external sound on the membrane. It's unfounded and I can't erally unwrap the idea to figure out how it should be in theory, so I wanted to hear from anyone who have tried an current-out amplifier.
Yes, most amps are voltage amplifiers, with low output impedance. Some however, are voltage-controlled current sources, with output current proportional to input voltage and high output impedance. Current buffers are not these, as they have low output impedance. IIRC, the FirstWatt FW1 was/is a high output impedance design.