Stacked Large Advents v Cornwalls v Klipschorns

I fell asleep on the Advents, But then I WOKE UP with the Klipsch!!!!
It's just something about that HORNY HORN'S.

Had all 3, in the order you have them listed. The Advents were superb back in the day. However no match for the Cornwalls, and certainly not for the Khorns. As mentioned above, your room is critical for these speakers to sound right. And what you power them with as well. Hint- Wil Vincent from Autospec is selling a Baldwin modified amp here, One of the best sounding amps I heard with the Khorn. 

There is no contest. When I was a teenager in the 70's my older brother was sold on Advents. I challenged him to an A/B test with my Klipschlike Fraisier IV's..They blew his Advents out of the water. He went and bought a pair Heresy's the next day

Frazier IV's. Been a long time. Frazier's were great speakers

   I have had experience with three different sets of stacked Advents, they are very good and fun to listen too. All sets had been recapped with new woofer surrounds. They can deliver some wonky impedance issues so be aware of that. 
   On to Cornwall’s, several sets as well, some with Critz woofers and crossovers, a pair with Mundorf Supremes, one pair stock. I like Cornwall’s, in my opinion much more (dynamic), might be the word, and as expected preform beautifully with tubes. 
   Lastly the Khorns, I’ve experienced a couple pair. One pair was highly modified using ALK Eliptrac horns. The other pair was stock aside from B&C tweeters in aluminum wave guilds, they both sounded fantastic.
The pair with the ALK horns and mods resulted in around a 110db efficiency, these were powered by a Truth pre amp and a SET tube amp of about 6-8wpc. I wish I could remember the amp, maybe a Bottlehead, the tubes look like hydrosodium light bulbs. These were absolutely stellar, everything played was just fun to listen to, when music you normally don’t like gets your toes tapping then they are doing it right. 
The main comparison would be efficiency, stacked Advents are exponentially less efficient than the Heritage speakers by comparison, so the question would include a comparison of the equipment down the line as well.