I am very happy with the changes wrought by the mods I have done on my second pair of SR60i thus far, but I really want to caution the OP and others considering the mods:
- if the Grados you are about to mod are your ONLY decent phones, I would strongly consider limiting yourself to experimenting with pads while you save for a pair of RS1/Ms-PRO.
- if you are prepared to run the risk of potentially ending up with a pair of phones in need of new drivers (or worse, new housings), my advice is to try to be prepared to do it in one session. I must have had the cups apart 20 times over the course of the weekend, and each time I came away wondering how much stress I had put those solder joints under. Fortunately, they seem to be designed to take it, at least so far.
- I dont have any wooden cups, but even with the plastic the effect of opening the cans right up is undeniable, and I have a pair of stock SR60s to confirm this. Sticking with the plastic, you will almost certainly end up with something fairly ugly by the time you get around to replacing the outer grill - trust me when I tell you that the sonic improvement is absolutely worth it.
I would dearly love to blindfold some of the skeptics who would describe the impact of these mods as 'placebo' and switch between my stock 60s and the 'BV60i' : even with the button and stock grille still in place, I believe you could seriously confuse folk at a meet with your humble 'SR60' hooked up to something with serious bass punch.