Amp for JBL 250 Ti

you should use Reyaudio mono amps(top model) never heard thise jbl's better period.

I responded to your post on AK for a Mac amp. For other potential amplifiers you may want to consider an with a higher current high headroom amp like a Mark Levinson 23.5 or a Jeff Rowland model 5. Super high current and I think better bass control. Both can be had at a more manageable price point

I would use McIntosh amps.......

It's rather confusing - do I need the high current traditional amp like Krell or Mark Levinson or does the autoformer Mac do?

Autoformer is going to be more circuitry to the amplifiers design and signal path. The 250Ti should not have any wild impedance curves not sure if they are 8 or 4 ohm load. Some reason 6 ohms comes to mind. In any event they do need power so your options will be a Mcintosh amp 300+ watts/ch or a lower powered (200+w/ch) higher current amp like a levinson krell and so on.

My experience with the high current/headroom type amplifier is that they will give you better bass control. Much tighter bass and midrange is clean and crisp from this type of amp. The 250Ti from what I remember was not your typical JBL monitor west coast sound but a neutral balanced sound.

Mc-2300 are not an autoformer type amplifier. I'm not a big advocate of the autoformer for the reason I stated.
This amp seems to have endless power for whatever reason. they have a very similar sound to my Mc-3500's Good candidate for your 250Ti