Thanks to lurking the head-fi forum for several years I managed to bulls eye my listening goals first go on each, with one tube and one solid state system which I enjoy greatly:
Source for both: Sonos -> Benchmark DAC1
Tube: WA3+ with Amperex 6922 and Tung Sol 5998 -> Sennheiser HD600
SS: Violectric V200 -> Hifiman HE-500
I may be adding a Violectric V800 for a source DAC in the future. To give a flavor for my personal preferences and bias, I listened to both the HD650 and HD600. I preferred the HD600. Then the HE-500 sounds to me like the HD600 with the high end above 1500Hz down 2 dB, but with lower overall residual distortion, though it should be noted that the HD600 already has very low distortion to begin with. I've had the tube system for over a year, the solid state is a more recent addition. Very happy with each for their respective capabilities.
I will be attending the meet and bring the SS system. The V200 has the internal USB option which I will run from a notebook source using WinAmp. Will have AIXCoustic Electri-Q EQ in WinAmp for folks to hear what happens adding a +2dB shelf EQ above 1500Hz on the HE-500 vs no EQ.
Looking forward to meeting everyone, thanks to all the forum contributors (esp SkyLab and Big Poppa) which helped steer my search.