325 has better bass , more detail.....some call it very bright, I did not find that to be the case with mine.
Better build quality.....L cushion, leather headband.
I definitely call it a better headphone, however some like the SR80 better.
It is tuff to say if it is worth the difference in price, as the SR80 is one of the best bang for your buck headphones that you can purchase, imo.
The higher you go up in the chain, you get less bang for your buck, but the sound is better, just not by leaps and bounds.....that being said, I just loved my 325i....a very detailed, in your face headphone.....fantastic cans for my genre, which is basically rock, blues.