Amp for JBL 250 Ti

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

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

I didn't think autoformers were used until the Mc2500 or 2600 in the bigger industrial look amps and I'm not sure about any of the blue meter Mc amps
As far as the matching Ohm outputs that would be the different locations where the power transformer is taped from not necessarily an autoformer. It would be more common to see multiple tap locations on tube amplifiers than solid-state.

My Mc-3500's have even more tap positions than the 2300 but they were for industrial applications rather than for sound reproduction

I'm not saying the Autoformer is better or not for sound reproduction. All I'm saying is I dont prefer it if your speaker system has a stable impedance curve like your 250Ti
If you are driving a pair of electro-stats or maggies that can dip below 1 ohm in certain frequencies then an autoformer will benefit you a lot. A levinsen krell and the likes are really not meant to drive any impedance's below 2 ohms and really need to be 4 ohms or higher.
You're asking for amps that will drive your JBL 250Ti speakers. I'm just giving you more options and what to expect on performance. I'm definitely don't want to start a debate on Autoformer or no Autoformer or MC vs Levinson Krell Pass and so on
Its all great equipment solid craftsmanship engineering but they all have strengths and weaknesses. There is more to mating a speaker to an amplifier. Understanding the principles of what a speaker needs to preform at is peak will help you make a wise amplifier purchase for your speaker.

Autoforms in Mcintosh amplifiers give the end user the option to match low impedance curve speakers to the amplifier autoformer transformer and be able to operate the amplifier safely. As far as sound quality with Autoformers thats a whole other debate on AK you can read about.
I think matching a speaker to an Mc autoformer amplifier becomes a little more experimental for optimum sound. You need to spend time taping your speakers to the different terminals and listening for the best results.

I have heard of some owner bi-wiring in this example - taking two of the four speaker wires, taping to the 4 ohm terminals/com & connecting one set of terminals at the speaker - taking the other two speaker wires, taping them to the 8 ohm terminal/com & connecting to the other set of terminals at the speaker. I only read about this and I would get more guidance from Mcintosh before attempting this.

Autoformers add additional cost to the amplifier. I think you would be better off putting more $ in clean power than having an autoformer type power amplifier. JBL was never know to build low impedance speakers and if anything were always very stable and built for gobs of power.