The PS500 was significantly more even to my ears. Just with a huge dropoff in the low bass.
And honestly part of me wants to get to "understand" Grado because I just love how they're made and the craftsmanship. Even if they're not my go-to headphones I'd really like to have some and love them for what they are.
If this is the case then why don't you just get a pair 80i's, you will get the classic Grado sound signature from these headphone, and you will definitely get too understand Grado with these…in a big way, and save yourself a lot of money.