Basic question about power/watts

40 watts is plenty.  However, not all 40 watt sources are created equal.  If you have a 40 watt amp with a huge power supply and all the current capability, you'll be fine.  but if your 40 watt amp is a typical amp with just bearly what it takes to get a 40 wpc rating, it probably won't handle the heavy load the your speakers are.

But if you buy a 600 wpc amp, you can be pretty sure that at lower power it has all the power and current necessary to excel at the lower power. 

Make sure your 40 wpc amp is getting adequate power.  it should be plugged directly into the wall or something with high current like a PSAudio power plant.  10 awg power cord.  avoid the passive power conditioners.

Jerry

The reason to get a high-powered amplifier is so that when musical peaks come, you will have enough power to reproduce them. For highly compressed pop music, that isn't an issue. But it is an issue for anything recorded naturally. If the amp is limiting, the sound will be strained and/or dull.

Hi timintexas!  Your amp is probably clipping and the Maggies will reveal that to you by sounding awful. They are unfogiving of poor input signals. The Maggies are a straight, low impedance load. Not many amps can really feed a flat 4 ohm load. Depending on which model you have, the Maggies may be closer to 3 ohms. Check you amp's ratings. If the power into 4 ohms is NOT double the power into 8 ohms, the amp may have a problem with the Maggies. Maggies are not efficient by any stretch of the imagination. Most commercial speakers run around 86 db sensitivity (spl). Maggies are closer to 80 db.; too bad, but pretty close to true. That means they need about four times the power than the average speaker. Watch the meters on a tape deck while playing music. Watch for a difference of 10 db between various musical passages. That difference requires a 10X power increase from your power amp. A real peak can easily require 20 db more "juice." That's 100 X the power for an instantaneous burst of sound. Suppose you amp is running along nicely at 8 watts, that should be getting close to "loud" on a average system. Somebody hits a drum, blasts a trumpet, or knocks over a chair and you need 800 watts for that 20 db bump! Ouch! That's why people have huge wattage amps. 200 watts is only 3db (the smallest difference in loudness the average person can hear) louder than 100 watts, which is only 3 db louder than 50 watts, which is only . . . etc., until you realize that 200 watts is only 20 db lounder than 2 watts! Watch those meters again - 20 db sounds only about 3 times louder to the ear. Suddenly, you realize what all the talk about amplifier headroom is all about. An amp, frequently asked for higher power than it is comfortably provide, is going to sound bad. Period. You have seen reviews quietly mentioning that you need a  serious amp for Maggies. They will never sound dynamic and smack you in the chest when the cannons go off in the 1812 Oveture, but - with the right amp - they will give you detail and clarity that few other speakers can approach.

Now you can understand why some folks are so enthusiastic about high efficiency speakers! A speaker with a 100db spl (Zu Audio, Klipsh, and a few more - not many) rating needs only one one-hundreth ( yes, 1/100th) of the power that Maggies need! Those speakers are owned by the guys with the 9 watt (or even less) tube amps! Put one of those speakers on your 200 watt amp and you will get absolutely awesome dynamics! Happy Listening!

@timintexas I think part of the issue is that the amps ratings are given for continuous, static, steady-state power. When delivering continuous, steady-state power, then power can be rated in Watts and measured as current delivered at a certain voltage across a certain resistance and/or given off as heat. The real issue with your situation is that the amp’s rating is only a starting point; all it means is that it can furnish 80 Watts into 8 Ohms of impedance. Impedance is measured in Ohms, but it is defined as resistance in an AC (not DC) circuit. The music signal is AC and inductors (like speaker coils) and capacitors (like power supply capacitors and capacitors that ‘couple’ one stage to another present resistance which dependent on the the frequency of the signal. An inductor’s impedance varies directly with the frequency; a capacitor’s impedance varies inversely. Music presents a host of frequencies all at once. But I digress.

The point I most wanted to make is that once the DC bias has been set for tubes or bipolar transistors, there is little that is steady state about driving a set of speakers like the Magnepans. The difficulty they present to the amplifier is that their resistance (impedance) they offer to the amp is ‘spastic’ as one person put it above. For one frequency they might offer 2 Ohms of resistance (usually lower notes), for another it may be 16 Ohms; meanwhile the amp’s designer may have as many as five voltage rails inside the amp, each with it’s own power supply which the amp is supposed to switch in and out as needed depending on the load it is presented. A speaker’s spastic impedance curve can simply overwhelm the amp that hasn’t got gobs of reserve power stored in capacitor banks and/or mediated by impedance matching output transformers or the like.

Of course, if an amp has this kind of reserves, I’m sure they would let you know it.

Considering things from the speaker side, The manufacturer may slap a rating like ‘4 Ohms, 255 Watts’ on a speaker, but unless you can see an impedance trace for a relevant frequency spectrum, the figure means very little, except it is going to take more power to drive it than an 8 Ohm speaker.

In my opinion, for which there is no fee, if you’re serious about listening to the Maggie’s, you need to start with the question, ‘Can anyone recommend an amplifier that can drive my speakers?’ Add the exact model number, and, if possible date of manufacture or S/N. You could add stipulations like preference for tubes or solid state, balanced or unbalanced connections, phono stage (or not), budget, etc

You can post a description about your system under ‘Virtual Systems,’ but you must include a photo.

Good Luck!

People are very silly and wrong when it comes to amps and speaker efficiency. You yourself said that it's "unbearable" with the knob at 11 o'clock and a 600 watt amp will just be unbearable (but sound the same) at 7 o'clock.