Fantastic write-up, Fran. I also appreciate the detail you've gone into regarding support for build in case a newer builder is considering it.
I've been wanting to put together some form of Aikido as headphone amp for a good while, especially after hearing looser101's awesome high voltage build last November (which I felt on par with a single-ended B22, perhaps beating it out slightly). I also want to get a pre-amp out of the deal, so this looks like a winner to me.
The max certainly is a great amp (better than most commercial offerings I've heard). I'm glad to hear your impressions about the Aikido as they are though, as they seem to point to exactly to what I'd like improved/changed about the max's sound to bring it up to the next level.
It's funny that you should mention it as a large amp. I suppose it is, but one of the reasons I'm excited about it is that it will be a down-size for me, in terms of size
I'm still looking at casing options, but that's something I'm going to leave open until after I've actually put the amp together. The three sizes I'm hovering between at the moment are 12x8x2 (tubes sticking out the top), 12x8x3 (if I decide to fit a hammond 159zc choke (60mH, 2a, 0.7dcr choke) in there), or 12x12x4 if I feel cramped (I don't want to go that large though, which is why I'm using a TREAD).
Also, thanks Fran for pointing me to SKA. I might pick up a GB150S amp and supply in a few months as reviews look good compared to price.