That impedence is rather trivial since the makers of the phones have obviously factored it's cut off point in. It just gives the amount of load resistance the phones give out. Another point is efficiency, which i'll explain below before i explain resistance, maybe Ijan can add in a thing or two in case i miss anything out.

Resistance of the cans themselves -

Well resistance indicates the amount of load a can poses to a source, like ijan said in another thread, this resistance is coupled with reactance, and non linear, but we'll leave that aside for a moment.

A good example is;

If you put the same amount of current and voltage (power in watts is the same), into 2 cans. One labeled A @ 75 ohms and another labeled B @ 300 ohms, the result will be like this (numbers only for education)

Can A = 60 dB attenuation
Can B = 80 dB attenuation

It means from an electrical standpoint, if both are fed the same signal, more power is lost on the one with a higher level of driver resistance.

Efficiency-

Let us get back to cans A and B, and use the same amount of power as described earlier. Let's say 100 miliwatts consumed. You must understand that even though can B's impedence is higher it does not mean that a 300 ohm can will sound 4 times softer (not factoring in Logarithmic curve) than a 75 ohm can. There is another factor. Efficiency!

What happens if can B with 300 ohms takes up all that power, YET! It turns 90 percent of that power into sound, and 10 percent wasted (heat, magnetic field loss or hysterisis) and the 75 ohm one is only 50 percent efficient, so you can say that even efficiency plays a bigger role in cans rather than just impedence.

ok, let's put it this way, (assume that both are fed the same amount of wattage regardless of load resistance, meaning both take up the same amount of power)

Can A 75 ohms = 10 percent efficiency
Can B 300 ohms = 100 percent efficiency

Which would be louder? obviously B, and when you combine the both ideas of resistance and efficiency, the conclusion is (if you don't like reading all my rubbish), that Efficiency and Resistance are a combo, even though higher resistance cans are harder to drive, they are in some cases much more efficient

Ok, now on to the resistance changing sound part

Resistance can change sound by the virtue of being a low pass filter, meaning it let's the lower frequencies pass and the higher frequencies are blocked. The theory behind it is, you can usually use A) Inductance or B) an RC filter (let's just assume B, because i can't calculate inductance worth a damn).

The formula for frequency cut off is Fc = 1/2pi x R x C

Fc being cut off, pi being apple pie, R being resistance (of the coil plus the new load) and C being (capacitance, parasitic or not)

The capacitance of the cans is quite hard to measure, maybe i'll get a new Fluke 189 to test since my 179 is only accurate to the nanofarad level. Although you should assume 100 pf for good measure. Just fill in the blanks and you'll have a cut off!

Adding resistance helps cut off unwanted higher order frequencies, leaving better or too much bass in some cases, it some cases it's a good thing, in others, it's even worse. So be wise.

Oh yeah, don't use those cheap resistors that have a tendency to drift (electromagnetic randomity and change into heat as the electrons bounce around), so buy mine i has RN55 and RN60Ds from Vishay Mind the unabashed sales pimping 

u berani use his SR80? his gf pakai pegang the wording alsi kena tiau, if u ppl, hahaha!

j/k

Hoi PcWork, it's been well over a month now since I asked you to quote for a bunch of cables that I want. You asked me to give you time but you've not replied or explained the delay. Do you want to make me the custom cables or should I look elsewhere?

wat is ghey??