Garage:
My LV is in transit but I'm planning on a 24 volt version with 6GM8's (bought a few some years ago before the prices went crazy).
Will you be building a headphone driver as shown in the 24 volt Aikido manual
http://www.tubecad.com/2008/02/04/24V%20Aikido%20Stereo.pdf or power your phones directly with a big output cap? You might just get away with it on the HD650's as they are 300 ohm 'phones but I don't know about the other 'phones you mentioned. I'm planning on the solid state HP driver hard-wired off board of course because it will need some heat sinking.
What will you use for a powwr supply? Switching wall-wart or a linear supply?
FYI, I've just finished building an Aikido 9 pin All In One HPA/LSA in the HPA version using 6CG7's and 6DJ8's. It's not completly broken in yet and I'm waiting for some RTI power supply bypass caps shipping with my LV order but I'm intrigued so far with the performance. I'll go out on a limb here but I think the Aikido design uses tube non-linearities against itself to lower distortion and decrease power supply noise. Tube rolling is to my mind is finding the tube non-linearities that most appeal to you. The Aikido as I've experienced it so far is more independant of tube rolling perhaps because of the afore mentioned non-linearity-cancelling circuit design. Just my 2 cents worth.
In my humble experience you need to run a new amp for at least 48 hours (with signal) to break-in the tubes and caps before coming to any sonic conclusions.
Let us know your progress!
Cheers, Steve