Sennheiser HD 202 II and ASUS Xonar DG settings

Hello, I recently got a new pair of headphones - the Sennheiser HD 202 II Professional. (http://www.amazon.com/gp/product/B003LPTAYI/ref=oh_deta...)
And then got an ASUS Xonar DG PCI sound card (http://www.amazon.com/ASUS-Channel-Sound-Card-XONAR_DG/...).  

I used to just use my mediocre logitech 2.1 speakers or an old $10 logitech headset so the sound improvement with these Sennheiser's is quite noticeable. I have not noticed much difference with ASUS Xonar DG sound card vs. the onboard Realtek HD sound but I'm not too surprised by that as my ears aren't trained to notice subtle differences. I did notice with the Xonar there is no background noise/feedback/interference like I was getting with the onboard which is good.

But I am wondering if I have the optimum settings. Currently I have the Xonar DG driver settings at: 8 Channels, PCM 96 KHz, "GX" enabled, set at the "Pro-Gaming mode for 32-64ohm headsets" as my headset has 32ohm impedance. I have not messed with the EQ settings...I notice if I turn on the Dolby Headphone option it mostly just gives everything that fishbowl/echoing sound. Most games I've tried have their own surround sound option in-game which I use and works pretty well.

I went into the W7 sound settings and set it at 24 bit, 192000 Hz quality and selected the 7.1 Surround setting.

I have found that music sounds best in WMP with the SRS WOW effect turned on and the EQ set at "5, 0, 0, 10, 3, 0, 4, 9, 2, 4" from left to right in the EQ.

Also I've wondered what checking the box for PCM under SPDIF Out in the Xonar settings does? It doesn't seem to make any difference in sound to me.  

So if anyone has any tips/recommendations for optimizing settings with a setup like mine I would appreciate the input.

Oh and if anyone has opinions on the Sennheiser HD 202 II and/or ASUS Xonar DG feel free to say so. At ~$25 each I think they were good deals personally.