McIntosh autoformers vs direct-coupled output

I have ML 11As and picked up a McIntosh MC452.  I spent a lot of time trying to figure out why I couldn’t get some instruments to sound natural, especially violins and pianos.  I found and bought an older MC7106 6 channel directly coupled amp for my center and future surrounds.  I tried bridging two channels and connected the 11As.  The MC7106 brought a more crisper sound to the instruments, it wasn’t perfect since the sound felt a bit thinner probably due to not having enough current.  Nevertheless the instruments were less muddled than the MC452.

Let’s just say I spent a lot of money working around the MC452 not realizing that it was the primary reason I wasn’t happy with the sound.  It’s a great amp, just didn’t fit my preference paired with the 11As.  

What I learned through demoing a bunch of amps is that ML panels naturally roll off highs and are a tad warm.  Match it with a Mcintosh ss amp with autoformers which is also warm, just doesn’t makes good match, for me at least.  It’s all a matter of personal preference, it may work for some.

I liked Luxman the most, especially the 900 series separates, but budget constraint ended with with the 509X.  Others amps work great as well.  Constellation amps, even their entry level line, seem to resonate as well with ML owners, though I never got a chance to demo then myself.

1: Full range CLS/CLX, 
2: Two ways with passive bass driver. 
3: Or two way with active bass diver? 

George, I think he was referring to option 3 from your original post.

@broockies, 

It all ends up what sound signature you like listening to.  Two similarly measured amps can sound different with the same speakers.

As George mentioned, the ML panels go below 1ohm in the higher frequencies.  From my experience, the amount of power needed to bring out the full potential of the panels is related to the size of the panel itself.  What could easily drive my older Source MLs speakers, sounded anemic with the 11As.  

With MLs if you want a crisper sound signature go with direct coupled.  If you want warmer sound with more rolled off highs then go with autoformer.  If going directly coupled, my recommendation would to make sure the amp is rated down to at least 2ohm.  Otherwise, go with autoformer to make sure you provide enough stable power to the speaker.

I do believe that matching preamp and amp is the way to go.  Only reason I mentioned alternatives is that a used McIntosh amps sell far higher on the used market than far newer competitive brands.

Broockies, the Expressions are 13A’s, one up from the Impression 11A’s.

Expressions are great speakers, they would definitely need some decent power to drive though.  Not necessarily in watts, they need a solid power supply with enough headroom to reach the 0.7 Ohms at 20khz.