Hi there,
Well, ordered some K701 pads to put on my K501 after reading all the rave about the transformation here. Finally had a chance to give them a listen over Christmas and...
Well, I prefer the stock K501 pads.
The K701 pads on the K501 take the a little of the airy, open sound of the K501. Sure the bass is increased but it becomes muddy and overblown. This is without foam disc and with the pads mounted in the correct way (thick part back). I also find them more comfortable with the stock pads.
My dad recently bought some K601s (just to annoy me basically). And I must say, they are in a different league to the K501. More detail AND less harshness (yes, it's possible). Instruments have more body to them; they tend to be very edgy but also thin on the K501. Soundstage is also bigger to me. Bass quantity is comparable but it's deaper and more impactful on the K601. The K601 is just more pleasant a listen and is just that little bit better at everything it does.
PS: I initially mounted the pads with the thick part at the bottom. That sounded really awful! It's amazing how the pad position can change the sound.
Just my input on the story. If you like the mod, by all means keep going, don't let me stop you.
I just thought people who own the K501 might want to read a slightly more moderate opinion.
Cheers,
Piffles.