My modded Porta Pros features grill mod and around ear-pads so they sound very open and nice, as far I remember. It's been a long time since I listened them though. Later on I used ksc75 drivers on Porta Pro headband and pad mod setup because I preferred ksc75 sound back then. Ksc75 are also grill modded. Last time I used Porta Pro ksc75 hybrid was when I was stuck in a hospital for a full week and didn't want to bring my better phones there. Sound was too bright for my present more experienced ears, and I had to EQ treble down a bit. I believe Porta Pro drivers would be now what I'd prefer over ksc75, at least on my modded setup. I don't have access to them before next weekend, but it'll be fun to listen them again and will do some comparing with PX-100 then. But seriously, PX-100 II are great, I compared them to HD650 yesterday very quickly, and I don't wonder if some prefer PX-100 II over HD650. PX 100 II doesn't seem to have certain veil that HD650 has, at least on my setup.