Correct, to a point. The avaiable voltage is only part of the overall product of the device. The available current is a big factor, running with magnetic headphones.
No, its the voltage that determines how much power is available, not the current, since the output impedance of an MP3 player is essentially negligable compared to the headphones.
Note that the battery capacity is stated in Ah (Ampere-hour) terms.
This has nothing to do with anything in this thread.
Capacitors are a wonderful thing; several of their properties are uniquely useful. One of their most useful is that they will, if connected in series with a signal, pass the alternating (AC) component of the signal, and eliminate (reduce) the DC component of the signal. Anything in series with the output can, inevitably, color the sound of course.
This is oversimplified. A capacity in series with an output impedance forms a high pass filter. Hence, capacitively coupled outputs are generally not prefered in these applications, and modern designs are moving away from them. Direct coupled outputs in practice tend to produce a more even frequency response and lower overall output impedance (since they capacitor contributes its own complex impedance).
The primary difference that I refer to, between the v2 e200 and the Clip series, is the difference in available current (not the similar voltage).
You are mistaken. There is absolutely no difference between the e200v2 and Clip series. Both use identical DACs with equal power output.
Also, its not really meaningful to talk about “available current”, since that is a function of voltage. The term you are looking for is output impedance, which describes the ability of an amp to supply current into a load independent of voltage. However, since all mp3 players run with Rout << Rload, the current capacity is essentially identical, or at least it should be or the player will sound really bad. Instead, output impedance matters because it determines the dampening factor (basically how well the amp can surpress distortion in the transducer) and in the case of capacitively coupled designs, the evenness of the frequency response.
FWIW, if you want to know more about this stuff, wikipedia actually has a really pretty good overview: