I have Sennheiser PC350's. Yes yes, you can bash me to hell and back again for having them, but first know I got them at a massive steal of 95$ a few years ago, and they compare, driver wise, according to a Sennheiser rep to HD595's, but with most users reporting they end up around HD555 performance. Which is good enough for me, considering the mic has stunning quality, I would often get questions on what I was using as they hadn't heard such a clear mic before.(I mainly play games.)
However, I've always felt they needed "More", say to speak. I know about the Hero mod and hope to do it some day, but I always felt like my Soundcard wasn't giving it enough JUICE.
My current sound card is dead, so I am most likely going to pick this up at the awesome price it is right now:
Has no internal amp, like the USB models.
I'd be willing to shell 50-75$ for an Amp to drive the PC350's. They are 150Ohms as stated in the title, and I read many reviews of users with PC350's saying that after adding an amp, their lows and mids improved considerably and there was sharper detail.