Beyerdynamics DT880s and I have no idea what the stock tubes were as I bought it used and it came with a whole assortment of NOS tubes.
What the Sylvanias did is to move the presentation forward and greatly increased the presence - with the RCAs everything sounded kind of distant and washed out in comparison.
The tubes had the same effect with my AKG 701s which are now on their way to a gentleman in Hong Kong. He went on quite the shopping spree and also got my Sonic Frontiers preamp and 3 pair of speaker cables. Christmas for Mr. Chung!