IMO, the sr325 is a scam, why? because it appears that grado added the aluminum cups for better/different sound from the 225, but the aluminum cups dont actually play a part in the sound, why? because within the phones, there is another plastic section that covers the whole exposed aluminum pieces, thus, the aluminum never even played a part in the sound because the sound waves bounce off the inner plastic enclosure instead (no, I'm not talking about the plastic section that contains the driver, there is another plastic piece completely covering the insides of the aluminum cups so i am convinced that the difference is all about the driver selection versus construction differences. also, when i compared the 325 with my 80, I could barely tell the difference between the two. as you go up the grado lineup, you'll quickly find that they sound very close to each other, heck, I doubt anybody can actually tell the difference through blind testing