[darknix]

OK, I slept through my Physic classes years ago

So, what is the impact of the voltage and current on headphones?
Here is my guess:
Assuming the phones is at 55ohms and 91dB/mV
Does it means?
HIGH V=HIGH VOL?
HIGH A=?

 

[Golden Monkey]

I'm not sure what you're asking exactly, but as a general rule, low impedance headphones require more current (instead of voltage) and higher impedance needs more voltage (instead of current). In practical terms, the headphone jack on an iPhone or portable cd player is driven by an opamp and delivers very little voltage (otherwise you'd have dead batteries very quickly), and that's why ear buds and phones for portable use are low impedance. Tube amps supply a lot of voltage and voltage swings better than solid state, and don't run out of overhead easily (overhead being basically power reserves during very dynamic passages), so a high impedance voltage hungry (high z) phone like the HD650 will need a good tube amp to shine or they sound slow and veiled (this is just an example). These are very broad generalizations, mind you, and just a couple of examples.