Is powerfull Amps only for low sensitivity speakes?

I reject the notion that inefficient speakers are inherently superior sounding. Not based on my listening experiences. In terms of sound quality there is much overlap between various categories of speakers . Low, moderate or high efficiency,  excellent sounding speakers exist. 

Now someone may prefer lower efficiency speakers and of course that’s fine. I just find that people who post very generalized blanket statements do reveal a lack of knowledge for a given topic. Ironically their blanket statements are presented as indisputable fact which they most clearly are not.
Charles

inefficient speakers hide noise.  :)

Kalali writes:

"An additional point against using high powered SS amps driving extra efficient speakers is most SS amplifiers produce higher levels of undesirable (higher odd order) distortion within their first watt or two just like but not quite as much as when they are pushed near their clipping limit."

This was - maybe sometimes still is - the problem with solid state amps and "lets drive the THD to zero" thinking. And yes, he is right withe the fundamental observation - tube amps naturally distort in a musical way; solid state tends to distort in a less musically way; but that is less a function of the devices than of how they are applied in a circuit. Honestly, that was all figured out and mostly mitigated decades ago. I even wrote papers on little pieces of how. So amps that behave that way are of the class of "bad amps designed by people who should have known better". A good solid state amp should have few nasty harmonics today. I’m frankly amazed at how far we have come in about 35 years. Heck, there are pretty decent sounding OPAMPS (!) today. really, again if you know how to use them (which most people don’t).

I'll also note that there is an implicit assumption that the amp is running in class-B mode, which, again, should never be the case for a serious high-end amp. It should run class-A for atlas a little bit (and after that don't bother me with subtleties, they are drowned out) :-)

Admittedly if you want bog power and low cost, it will sound like garbage, but that’s a COST issue, not a technical one. As I said above, the only problem with a big powerful amp is that you must spend money on that power and therefore didn’t spend it elsewhere.

Its easy to design "cost no object" pieces that are so impressive. Its much harder to make a great $1000 amp or whatever.

G

I have DeVore O/93's and an ARC Ref6/Ref 150se combo. The GS 50 is identical to the Ref 150se but looks much nicer. First, it is a very good and very quiet amp. Second, you are going to need a very good pre, and preferably an ARC. Someone else posted this and he was 100% correct-the GS150 is balanced only and you are going to want/need a fully balanced preamp. After that, you will need really fine cabling, particularly from the preamp to amp, but I have learned that my speakers are extremely sensitive to speaker cable too. 

But a powerful solid state amplifier allows you to use mostly far better inefficient speakers and avoid the distortion and non-flat frequency response of many tube amplifiers. Anyway, we are not going to persuade each other.

@willemj Actually I agree that a solid state amp with a lot of power is helpful with low efficiency speakers. If you do your matching homework, you can arrive at a pretty good solution.

Regarding the comment about tube amps- if the amp employs enough feedback, and many do, they will be just as flat as a solid state amp on a given speaker. All it has to do is act like a voltage source and tube amps have been doing that since the 1950s.

But there is a bigger issue- there is a lot more to high quality audio reproduction than just flat frequency response! The first problem of course is that such is just plain impossible because no speaker is actually flat. The next problem is understanding how the ear perceives sound and in particular how it perceives distortion.

Its that latter bit that is often where solid state and tube people part ways.

Distortion is heard by the ear as tonality. This is why tubes are often thought to be colored- because of the 2nd harmonic, which causes 'warmth'. People that don't understand that the warmth is caused by distortion often think that tubes just can't be flat; but that is not the issue!

But solid state amps have coloration too- and in their case as well, its not due to frequency response error- its due to distortion. Thinking that the small amount of distortion that solid state amps have as 'negligible' is a mistake.

The ear uses higher ordered harmonics to sense sound pressure (again, a fact that has been known for decades) so 'negligible' amounts are easily heard.

The ability to sense sound pressure is easily the most important aspect of hearing perception. The implication is its a Bad Idea to increase the harmonics used by the ear, unless high fidelity is not the goal.