Originally Posted by StanD
The math and formulae are not such a big deal. No calculus yet - lol. IMO most confusion comes from loosely defined terms that we use to describe what we are hearing. One guy's warm is something else to the next person.
My real take on this is:
There are a lot of Head Fi-ers who just want to buy an amp for their 'phones, and want to know what works without using any math.
The sensitivity thing amused me: how much SPL do we get at 1 Watt? But Wait! It's really referenced to 2.83 Volts into 8 Ohms! So it's really how much SPL do we get from 2.83 Volts driving a "nominally" 8 Ohm speaker. As you obviously know, is an 8 Ohm speaker really 8 Ohms? So let's standardize it and use a 2.83 Volt signal to the loudspeaker.
Obviously headphones are a pain in the butt compared to speakers. You can assume almost any loudspeaker is 8 Ohms and not get into too much trouble when shopping for an appropriate amp.
You can see that a lot of people get confused by the impedance and sensitivity and efficiency and voltage gain and how much amplifier do I need to make my headphones go?
As for loosely defined terms, try asking 10 Head Fi-ers which 'phone is brighter, the Q701 or the DT880s.................you may get 10 different variations on an opinion!