[Early B.]

8 watts with 97 dB speakers, so @ 40 watts with 90 dB speakers, seems about right.

Nope. According to Sanders, for 90 dB speakers, you need 500 watts to avoid clipping. But you won't know how bad your 40-watt amp sounds until you buy a 500-watt amp (preferably a Sanders amp). 

I used to justify buying large amps, not because of the power, but due to the manufacturer often using higher quality parts in their biggest (and most expensive!) amps.

[opnly bafld]

Plus 2 more SS amps of 300 watts each for the bass section.  The tube amps only have to play down to about 120hz in my setup.

On your speakers, but you are probably not using it all with an 8 watt amp for the rest.

[SET Man]

Hey!

   No surprised of why he wrote that article on his site there. Because he's trying to sell you his high power SS amps!

   Years ago when I was younger and just got into Hi-End audio, I always dreamed of having big speaker with lots of drivers and of course big high power amps! The highest power amp I've ever own was 250wpc SS amp, then I got curious about tube and got a 100wpc tubed amp of which sound way better than the more powerful 250wpc SS amp!
 
    Ironically, I ended up using 18wpc SET amps driving 94dB 6" single drivers with super tweeters for the past 20 years. Sound likes I'm going backward isn't it? 

[opnly bafld]

Sound likes I'm going backward isn't it?

Not at all, just found what works for you. 

[S Clark]

My line source speakers are 91 dB effecient, but still require power to control the stack of 12 midwoofers.  The back emf is a factor to be dealt with. I use a 200 wpc Moscode, and there is a noticiable improvement over a 15 wpc chip or tube amp even at similar volumes. There is a place for power.  But 1000 wpc for a basic tweeter, mid, woofer set up?????

[Stercom]

We should be talking how much current amp a delivers not watts. In my experience, a massive power supply and output transformer is the key to good sound regardless of topology or wattage.  Even a 2 ohm load can sound magnificent with low watts if it has massive current. Speaker sensitivity only tells us how loud it will play with 1 watt at 1 meter - nothing about sound quality.

[Freo-1]

My line source speakers are 91 dB effecient, but still require power to control the stack of 12 midwoofers.  The back emf is a factor to be dealt with. I use a 200 wpc Moscode, and there is a noticiable improvement over a 15 wpc chip or tube amp even at similar volumes. There is a place for power.  But 1000 wpc for a basic tweeter, mid, woofer set up?????

I understand the skepticism.  Unit I actually experienced it, I also thought it was a bit over the top.  Where this really came into focus is listening to symphonic./classical music.  Recordings that I had thought were congested for loud passages were no longer sounding that way. Piano, strings, horns, and vocals now all sound very natural.                                                                                                                                                                                                          Believe the crossovers absorb quite a bit of power.  Even though there is a momentary spike of power, the drivers are not overdriven.  We know that underpowered amps to speakers can damage drivers if overdriven.  Sanders states he verified this by use of an oscilloscope.  That makes sense. 

[Freo-1]

We should be talking how much current amp a delivers not watts. In my experience, a massive power supply and output transformer is the key to good sound regardless of topology or wattage.  Even a 2 ohm load can sound magnificent with low watts if it has massive current. Speaker sensitivity only tells us how loud it will play with 1 watt at 1 meter - nothing about sound quality.

Yes.  Sensitivity does not indicate sound quality. 


The newer SMPS are capable of supplying very high voltage and current, and have very low noise floor.  Even at 2 ohms, the wattage required doesn't change.  Luckily, very few speakers dip that low for an extended period. 

[Early B.]

Believe the crossovers absorb quite a bit of power. 

Yeah, a lot of people don't take crossover complexity into consideration when calculating power demand. It's a thing. Also, how low do your speakers go? If bass demand is low, then the need for power decreases. A single sensitivity statistic doesn't tell you much about the speaker.

[mgalusha]

I'm in the camp that believes most people don't have sufficient power. I've measured actual power used many times and have had guests try and guess how much power was in use at a given loudness, they are almost always surprised, in both directions, how loud a couple of watts is and how much power is used with even moderate increases in level.

My speakers are 97dB at 2.83V of input and I do have both low and high powered amps, SS and tubes.

Given the speaker sensitivity, the system will play quite loud with a 5W amp, but it's very dependent on the music being played. Something with very limited dynamic range doesn't need much headroom, but a recording with 15 - 20dB of dynamic range can eat a lot of power very quickly, every 3dB of level doubles the power required. If I get greedy with the volume control, it's easy to clip the smaller amps and occasionally even something with higher power. My benchmark has clip lights, I've only made them come on once and of course it was stupid loud, but it's 100/8 and 200/4, which should be enough with my speakers, and it is, almost all the time. I have an NC500 based amp that is double that, but of course it would only be 3dB louder.

That said, most of the time a few watts is fine, but sometimes I want to hear an orchestra at realistic levels, and that requires hooking up the "big" amps, with tubes that is 75wpc and that is a happy place.

A decent video on measured sensitivity and power requirements.

https://www.youtube.com/watch?v=qBuHmThA-7o

[Freo-1]

Yeah, a lot of people don't take crossover complexity into consideration when calculating power demand. It's a thing. Also, how low do your speakers go? If bass demand is low, then the need for power decreases. A single sensitivity statistic doesn't tell you much about the speaker.

The 3db down point on my speakers is 25 Hz.  That's according to the speaker builder. 

[I.Greyhound Fan]

Tried it both ways: a "low powered" 225w/channel AVA amp and 1200w/channel PS Audio Stellar M1200.
A fun experiment but stayed with the AVA amp.

An Amp Comparison: PS Audio Stellar M1200 and AVA Vision SET 400
https://www.audiocircle.com/index.php?topic=176173.msg1856501#msg1856501

Great write up.  You were spot on in your comments on the SET 400.  I felt the same way in my review of them for Frank.

[I.Greyhound Fan]

We should be talking how much current amp a delivers not watts. In my experience, a massive power supply and output transformer is the key to good sound regardless of topology or wattage.  Even a 2 ohm load can sound magnificent with low watts if it has massive current. Speaker sensitivity only tells us how loud it will play with 1 watt at 1 meter - nothing about sound quality.

Spot on.  Watt/ch, current and capacitance of an amp matters for my Magnepans.

[Freo-1]

Spot on.  Watt/ch, current and capacitance of an amp matters for my Magnepans.

The good news is that Maggies tend to have a fairly flat impedance curve. 

[FireGuy]

"You have your experience. Another has a different experience.  You can bet that you're both wrong in one way or another.  Just about everything I've learned in audiophilia is there are no absolutely correct ways of doing stereo (or mono).   Everything is a set of compromises in how to gain incremental improvement in sound reproduction."

 There is no perfect system or gear.  Better maybe,  but not perfect.  I interchange SS and SET amps all the time.  SET for my 95.5 dB efficient Omegas and the other amps for the 6-8 ohm Axioms.  Truthfully, the sonic results are predicable but never consistent.  Human factor?   Compromises?  Yes indeed, all day.

[jpm]

I recall Anthony Michaelson (Musical Fidelity founder) making a similar case for very high powered amplifiers some 15 - 20 years ago, though he referenced realistic SPLs rather than clipping. The MF Supercharger 550k and 750k mono amps were developed as a solution for people with low powered amps who wanted to have their cake and eat it. Along the same principles as REL with subwoofers, the Supercharger amps accept speaker level input and amplify that signal.

Here's a Stereophile review that adds a bit of info for anyone interested.

https://www.stereophile.com/solidpoweramps/907mf/index.html

[Freo-1]

I recall Anthony Michaelson (Musical Fidelity founder) making a similar case for very high powered amplifiers some 15 - 20 years ago, though he referenced realistic SPLs rather than clipping. The MF Supercharger 550k and 750k mono amps were developed as a solution for people with low powered amps who wanted to have their cake and eat it. Along the same principles as REL with subwoofers, the Supercharger amps accept speaker level input and amplify that signal.

Here's a Stereophile review that adds a bit of info for anyone interested.

https://www.stereophile.com/solidpoweramps/907mf/index.html

Thanks for sharing.  Certainly does add weight to the argument on the benefits of high power amplification.