Nice. I have a pair of Sylvania dual flat plates as well and I now prefer them to my RCA mono plates with the HD800. Along with the military Ken Rad dual box plates, they are the pinnacle of the 2A3. The Sylvanias, as you rightly point out, are for more refined phones, and the Ken Rads are to stomp all over orthos...
Do you like the HE500 better than the HE6 with the Stratus?
Third Eye, alas, I sold my HE500s! But I liked that combo a lot. Better perhaps than the HE-6, although the HE-6 are sounding very nice on my Stratus right now - especially with the Ken Rads. Better than EMLs. The EMLs enhance the HE-6's already sibilant-tending treble. But with the Ken Rads and even the Sylvanias, I was getting a very even, powerful, voluptuous sound from the HE-6s today. That being said, the HE-5s trounce them both! If you can find an old pair somewhere they are even more highly recommended.