Levinson 27.5

Hi has anyone heard 27.5 power amp? How does this compare to Levinson 523 (or so) series, as I have heard the latter - looking to drive Logan Summits
The 27.5 comes from the golden age of Mark Levinson. Well built, under spec’d (not like the 300 series) and very musical. Some describe the 23.5 and 27.5 sound as dark, but that was mostly attributed to the earlier 23/27 series.

I am not familiar with your speakers, therefore, I cannot comment on the compatibility, but if power is a concern, look for a 23.5 which IMHO, was one of ML best amplifier next to the 20.x series.
I agree with Brf, the 20.5/6, 23.5 and 27.5 series amps were the best I have ever heard from the Mark Levinson line. Unfortunately, newer is not always better.
I don't think the 27.5 amp would be right for the speakers. 100 wpc may not be sufficient. I would grab a ML3, 23 or 23.5. especially the 23.5. I have Martin Logan Monolith III speakers and I biamp with two 23.5s and it is wonderful. The ML3 I have was previously used to drive the bass drivers and the 23.5 used to drive the upper panels. Wow. Then I got another 23.5 to drive the bass drivers. I used 100 wpc solid state and 120 wpc tube amps previously and they didn't do it. The 23.5 can drive anything, are still one of the best that Mark Levinson built. The 27.5 is also wonderful, but 100 wpc may not be enough for the summits.
The tried the ml27 (not .5) with the original ML Quests, and it was a horrible combination.

I bought a 23.5 about 10 years ago following an "off the record" recommendation from a source close to Magnepan, who said it was the best amp they heard with Tympanis, ever.

It's still going strong and I would agree it is one of the all time greats.

Their later, Madrigal era space heater style amps have not achieved classic status and seem to all sell at significant discounts.

Good luck,