Are there really a bad misfits in the hifijungle out there

  You were listening to hi-end amps with high quality speakers. But apart from your example,  there are really bad combinations. One example would be an underpowered amp that is being used with a speaker that needs more power. Another would be a bargain basement amp that would sound poor with any quality speaker. I'm sure other members can give good examples of bad combinations.

Output impedance and input impedance of preamps and amps: need to be simpatico, or bad things happen.

Not easy that twoleftears.
Look at the McIntosh C-52 Pre. That one has on balanced output impedance 200 Ohms.
And if you match it with the Manley snapper monoblocks, that i think is a lovely mix. Then the Snappers have on the XLR 15 kOhms input impedance.
And i cant read the what the heck 15 kOhm is. But it sound a long way from 200 Ohms

Way back in the day I heard the Cremonas with Krell amps and the speakers sounded fantastic.

Happy Listening.

One man's bad combination is another man's glory. I've given up trying to understand how some people justify what is plainly to me abysmal sound.  :) 

Yep. Find a speaker that dips below 3 Ohms and suddenly they'll appear "discerning" of amplifiers. Same for ESL's. 

Don't get me wrong, there are a lot of very easy to drive speakers, thank goodness, which do not require 200 lb monoblocks to drive effortlessly, but the monsters do exist.

I have also personally found deliberately poor crossovers by Focal which deliberately choose to drop the impedance for just this reason. 

So you consider Thiels and Apogees monsters, Erik? Feed them properly and behold the magic...

The impedance curves are designed not to be deliberately/unnecessarily difficult, but to deliver the sound character, and especially the bass response, that the designer intended. 

Dave

Tube amps with output impedance of greater than 1 ohm are to be avoided! The June Stereopile has a review and test of the Rogers SE El34/KT88 integrated tube amp. Output impedance in the range of 6 to 8 ohms! Terrible! And distortion of 3% at 6 watts! $4K list price! If a SS amp measured so bad it wouldn't go into production! Such an amp will act as a tone control as it tracks the varying impedance of the typical speaker. The reviewer (HR) likes it!

I own three SE tube amps: a 2A3, a 45 and a 6BG6. Of all my speakers only the Heresy's are a good match (99db sensitivity). My PP tube amps (ST70, Dyna MkIII, Heath W5, D75 ... ) are far more practical and useful with most of my speakers!

And my Golden Tube PSE with its 3 6L6's per channel (18 watts) is also a better design than a SE amp.

Heidrun 9-1-2018

Not easy that twoleftears.Look at the McIntosh C-52 Pre. That one has on balanced output impedance 200 Ohms.
And if you match it with the Manley snapper monoblocks, that i think is a lovely mix. Then the Snappers have on the XLR 15 kOhms input impedance.
And i cant read the what the heck 15 kOhm is. But it sound a long way from 200 Ohms

Heidrun, twoleftears did not say that the two impedances should be equal, which is how you appear to be interpreting his post. He said that they should be "simpatico," meaning that they should be compatible.

In the case of a line-level analog interconnect, if the output impedance of the component providing the signal is equal to the input impedance of the component receiving the signal (which would be an unusual situation) the results will almost always be very poor. But 200 ohms driving 15K (15,000) ohms will almost always be fine.

For further elaboration, see my post in this thread.

Digital interconnections, btw, are a different story. In that situation the two impedances should be, and usually will be, essentially equal.

Regards,
-- Al

So you consider Thiels and Apogees monsters, Erik? Feed them properly and behold the magic...

Amplifier eating monsters, yes, absolutely. Please read my replies in the context of the OP’s question about misfits. It is not meant to attack your personal speaker/amp choices.

The impedance curves are designed not to be deliberately/unnecessarily difficult, but to deliver the sound character, and especially the bass response, that the designer intended.

This is not always the case, and I was referring to exceptions.

In the case of the Apogees, you are correct. They are purely ressistive and require the current to work against the magnetic force. In the case of ESL’s there is no helping that the entire construction is a giant capacitor. You cannot avoid the impedance dropping as frequency goes up. So, these are both misfits, and the term "monster" doesn't mean ugly or unwanted, but difficult to drive adequately, pretty much as your post to me mentions. 

In the case of the specific Focal speakers I analyzed it was a deliberate choice in crossover design. That is not to condemn all Focal speakers, but it was interesting that in many of the reviews for that speaker reviewers commented on how easy it was to hear differences in amplifiers.

Kosst : 

That's cool. Thank you for ignoring that and any future posts of mine. 

Blessed be,

Erik