I'll just plug the Coilcraft TriTuner again. Its small hex end is 2mm. It won't help with "blind" lower cores, but other than that, it's just dandy for (I believe) any hex core you'll find in any Pioneer made since circa the tube era.
Edit: Oh, and the Coilcraft also has the larger-format hex, for your aligning pleasure with older gear. (And a ceramic straight blade, too, but it's fragile - at least, I busted mine. I use an Aven ceramic now.)
For blind cores with the small hex format, I recently got a whole Aven set in the hope of getting one tool that's good for those. I haven't tried it in earnest yet, but I'm not hopeful. It is clearly a looser fit in the same cores that the Coilcraft fits with authority.