Just ordered a new WA6. Setup advice?

Hi all, first time poster here so be gentle! ;)

First of all, thank you all for contributing to Head-Fi. I've been silently researching this site while trying to decide which combination of headphones and amp to purchase. Needless to say, HF has been a tremendous resource.

I ended up going with the Woo Audio WA6 for my amp, which I will take delivery of tomorrow! As for headphones, I currently own a pair of Sennheiser HD-600 that I've had for years. To power them, I was using an ORB 11 SE which I hear is not very good.

What I will be mostly using my new setup for is CMSS gaming on my PC, and for music in those times that I can't use my main setup. (Less time to listen to it now that we have a 1yo and a 4yo running around.)

Since I am so indecisive, I ordered both the AKG-702s and the Beyerdynamics DT-990s from amazon. This weekend I will have all 3 headphone face off, winner stays, losers goes!

My questions are:

• The WA6 is my first tube amp, is there anything that I need to know before setting it up? 
• Out of the headphones I ordered, are any of them just not a good match for the WA6? I read on one of the threads that the W3 might be better for the DT-990s and HD-600s, if so, in what way?

Any other tips or advice is welcome.

Thanks!

-Sam

Thanks for the advice and the link. This is exactly the type of info I am looking for! I do have stock tubes for now, I want to hear them like this for awhile so I have a good understanding of the deference between the tubes.

Thanks again!

Thanks Redcarmoose.

Good to know that I can use any PC power supply cable.  I am so excited! 

Tomorrow can't get here soon enough.