Alas, the F1 and the B22 were not there, but the moth was. The EHHA is better than the Moth at effectively everything with the k1000, and plenty with the Grado. The speed, dynamics, power and tone were dead spot on. If they cost the same amount of money and I was only using the Grados, I'd get the Moth. As it is, the EHHA is $500 of parts to the $1500 Moth, and doesn't require periodic tube replacements to run. It's a no-brainer.
From aural memory, I feel comfortable stating that the EHHA is a better match for the K1000s than the F1 will ever be. They both exert a surprising amount of control over the drivers, but the F1 is not really designed for high-impedance headphones. I expect the Moth and the F1 to outperform the EHHA on my cicadas, however. In any case, I should very much like to test that theory.
Seriously, though, guys, the EHHA has gobs of power, just stupid amounts. Bill's build is a BJT version, rather than Mosfet, and it's also balanced. I'm sure that accounts for part of the power, but it was really remarkable.