How important is the efficiency of a speaker to you?

@atmasphere wrote:

I look at it this way- if you can’t drive it well with 100 Watts (in most rooms), its a problem.

+1

... and 1000 Watt amps that sound like music don’t seem to exist although class D is getting close with amps that can make 600 Watts or so.

Whether or not there’s a generality to your claim above, I can’t say, but I was surprised to learn that a 600W class A/B power amp from MC² Audio was perhaps even more "musical" sounding than a 30W class A ditto from Belles (which was a great amp) - that is, driving a 111dB horn/compression driver combo connected directly to their terminals (i.e.: actively, sans passive crossovers). Nothing sterile, tonally lean, mechanical or bright sounding about the Brit, I can tell you that, or whatever you’re implying about high power amps sonics. To boot its inherent noise level (in fully differential balanced mode) is slightly lower than the Belles (unbalanced), even with a 32dB vs. 26dB gain. I feared it would have been the other way ’round.

Btw. it’s 8 ohm EV DH1A drivers (that can also be had in 16 ohm versions), but without the intervention of passive crossovers, added to +110dB sensitivity and the amp being limited to run the load from ~600Hz on up, it’s a piece-of-cake job for an amp if ever there was one. Show me an amp running a 16 ohm load, full-range and looking into a passive crossover that will be running in cruise mode the same way. Not going to happen.

It’s not that I need that much power in my setup (also falling in line with the first quoted part of yours above), but I wanted to use the same amps in my 3-way active system from top to bottom, and ended up "replicating" the one used on the subs to begin with - one that turned out to be great sounding full-range as well (which I expected, given their reputation). As they say: if it sounds great, it sounds great.

@invalid wrote:

The amount of solid state amps that sound good with high sensitivity speakers is also limited, that’s why a lot of people choose set amps with these types of speakers.

Another generality, indeed this one is a myth that has gone on forever. From my experience it holds little to no bearing (I can imagine it would have been an issue back in the very early days when SS amps likely sounded like crap, or certainly worse than today), but you’re certainly allowed to take fuller advantage of a low wattage SET design when driving very high efficiency speakers, and such a combo can indeed sound fantastic. The inherent noise level of such amps sees some filtration through passive crossovers. Actively, another matter, and it’s also why I prefer SS amps in that constellation.

@phusis  It is not a myth, it has to do with the low output impedance of solid state amps.

@invalid --

That's not to say it can't be great match sonically. 

@phusis  It is not a myth, it has to do with the low output impedance of solid state amps.

Flea watt SET tubes produce a lousy loose wet noodle bass, sounds like a sloppy fart. It's not a myth. But, guys who listen to Diana Krall @60db may not know any better. When the bar is set so low, loose fart SETs might indeed sound spectacular for such guys.

Nothing sterile, tonally lean, mechanical or bright sounding about the Brit, I can tell you that, or whatever you’re implying about high power amps sonics.

@phusis The issue is that most amps made using feedback, which includes high power solid state amps, is that the output transistors usually limit the design's Gain Bandwidth Product, resulting in a loss of feedback at high frequencies (depending on how much loop gain is asked of the design). The result is distortion rising with frequency, which seems to be more audible than the actual distortion spectra created by the amp. Class D offers a way around this problem.

Another generality, indeed this one is a myth that has gone on forever.

The issue here is that a lot of higher efficiency speakers are designed for amps with a higher output impedance. Such amps try to make constant power rather than constant voltage; this is not a myth. The Power Paradigm is what was around before MacIntosh and EV started promoting higher feedback in the mid 1950s so as to cause their amps to behave as a Voltage source, allowing plug and play. You might want to read this article for more information.

Flea watt SET tubes produce a lousy loose wet noodle bass, sounds like a sloppy fart. It's not a myth.

@deep_333 You might want to read the article at the link above as well. This is not a myth; its a matter of whether the speaker designer meant for the speaker to be driven by an amp of high output impedance. If so, the bass will not be as described (although SETs in general do tend to have less impact on account of phase shift above their cutoff frequency, which tends to be quite high due to their output transformers).