Originally Posted by DarrenLays
How exactly does a "better amp" help anyways? If they're being properly powered, how does changing an amp change anything whatsoever?
I've always been curious about this, any help would be great
Lots of ways. (And I think you'll find that these are largely related)
1. Linearity. You touch on it when you say "properly powered," but just because your headphones have enough power does not mean that your amplifier is delivering a linear response. Non-linearities will result in distortion as the amplitude rises. Rise too high and you'll hit the voltage rail, which causes clipping (and nasty sonic effects).
2. Impedance. Okay, so your amp can
deliver up to 8 Watts RMS per channel, but does it? We can get into electrical dampening, but let's focus on power. Power equals voltage times current. Current will be determined by the impedance of the headphones. Higher impedance, lower current (which is Ohm's law, V = I * R). The voltage across your headphones is going to be determined by the relationship between the source and headphone impedance.
See, the output impedance of the amplifier comes from an electrical model we (electrical engineers) like to use where we reduce a circuit down to a voltage source and a resistor. The resistor is the output impedance, which we can measure, and the voltage source is the signal you want to feed to your 'phones. When we feed that voltage signal to your headphones, the voltage is divided between the output and headphone impedances. You want your headphone impedance to be sufficiently higher than the output impedance or else you're never going to get the purported power because your voltage is cut before it reaches your drivers.
3. Frequency response. This is related to linearity, but it is certainly worth considering on its own. A frequency response plot shows how much power from various signal frequencies is passed through the amplifier (0 dB means that 100% of the signal is passed; greater than zero is amplification, and less than zero is attenuation). Your music consists of many frequencies at different power levels, and this is another way to analyze how your amplifier will change the way it sounds. You generally want the pass band to be wide enough so you aren't rolling off your bass and/or treble.
4. Noise. Just because you have a very linear amp does not mean that it isn't inserting its own noise into your music.
5. Intentional distortion. Where would rock n' roll be without electric guitar distortion? Sometimes you want some color to your music, and an amp can add that. Most commonly we get this through tubes, as solid state (transistor) amplifiers tend to be more on the linear side.