5% THD to .000 THD SOUND

Specs are important to making sure you aren't getting ripped off. It's easy to rate a 35 Watt amplifier as a 100 Watt amplifier if you don't mind 10% distortion.  Used to happen very frequently.

Accuracy is also not necessarily what you buy. You buy amplifiers that make you feel good, whether it's in how they reproduce music, hos sexy the tubes glow, or how difficult their name is to pronounce.

THD is a bad thing, but it's not the only bad thing.  You can make almost any solid state amplifier have vanishingly low distortion if you raise the feedback enough.

Einstein said that not everything that matters is measured, and not everything that is measured matters.  We are still very much in that place when it comes to electronics. There's a separate thread going on about Hafler.  Measured great, boring and lacking in dynamics as you could possibly want. I don't know why. I'm sure with enough time and effort we could discover this, but no one has put in the time yet.

One criticism of amplifier measurements is also that we don't often measure linearity or have enough of a measure to explain how they would work with a particular speaker. That is, we can measure speakers, and we can measure amplifiers, but we don't have really good stats for predicting how they will work as a system, and how to correlate this to perceived behavior.

So, always listen for yourself, and spend the least amount of money you can to make yourself happy.

Best,


Erik

Let’s see...if 5% THD sounds better than 0.005% THD does that mean 10% THD might sound better than 5% THD? Sign me up!

You answered your own question -- the specs steered you into spending money towards the advertised distortion spec. Marketing strikes again.

THD specs can be misleading if they are taken at one frequency at a very low power output. THD, in general, changes as frequency and power output changes. I don't see how anything can be a flat zero distortion and if there is I can't see how that would sound any better than 0.01% at full load -- which is way below the threshold of hearing.

Tube amps generate second order harmonic distortion which is one octave above the fundamental, so both frequencies cannot combine and interfere with the signal from the source. This is like having the same instrument playing two separate tones in unison an octave apart, resulting what appears to be a warmer, fuller sound. But it's still distortion even though it can sound great.

geoffkait..My point is they BOTH sound great in my two examples of amplifiers having the opposite end of THD specs.. Arnet you the guy ( asstrophysisist )
selling those wacky trinkets to fool the mind into thinking the sound is better? Yeah I remember buying that stupid clock with a round magnet on it. and you banging your finger on the phone to activate the sonic realm of nothingness.. lol. If not you disregard.

One of the best amplifiers Kondo Audio Note $150k Kagura has 5% THD

I'm on the same track as erik_squires & when Almarg & Atmasphere see this thread I believe he will also be on this track. In fact all 3 of us have written very similar things in the past. Total Harmonic Distortion (THD) in an amplifier is a function how much global negative feedback you apply in the amplifier circuit. The more heavy handed you are with GNFB, the better the amplifier measures on the bench but the worse it sounds sonically because vanishing low THD creates other issues, for example, Transient Intermodulation Distortion (TIM).
So, what I can conclude for the Kondo AN Japan amp spec is that very little GNFB has been applied to this amplifier & to make this amp sound very its best one would need a heavily damped speaker that would put less stringent requirements on the amp itself to control the woofer's back EMF. I get this info by reading the Kagura spec.

SN/R  133 by Devialet and a lot less by Kagura.

this is again an effect of the high GNFB applied in the Devialet. The higher distortion in the Kagura creates a higher overall noise floor thereby degrading the SNR (vs. the Devialet). Having written this, in home 2-ch systems, unless one has taken extreme measures to keep distortion from AC power, foot falls, feedback from equipment racks, rumble from TTs to a very low magnitude, the typical SNR are 90dB or less. So, having 133dB is great by the Devialet but most home 2-ch systems are unable to avail of this. In fact, the SNR of a typical turntable is in the 55-65dB range & most vinyl/analog Audiogon members are in heaven spinning vinyl (over spinning CDs).

If the specifications are not that important to the sound, why list them?

listing specifications is a great way to ELIMINATE equipment from your short-list. It basically tells you what you should not bother investigating further.
With the Kondo AN Japan Kagura that might be a bad decision simply because of their stellar sonic reputation over the years. But Kondo AN Japan is an exception. There are other exceptions to this rul-of-thumb such as AirTight  & FM Acoustics. There must be more...

By looking at specs of Devialet and NOT knowing the prices of Kagura and Devialet I would of gone with the Devialet just based on specs alone for the impression of it being a  great sounding amplifier.  Ive read other discussions on forum and cant quite get a handle on why BOTH amplifiers sound great.

"sound great" is a nebulous term. It's been said to "sound great" by the press. Do you personally know these people in the audio press? Do they share the same listening habits with you? Do they listen to the same music as you? Do they have a similar room as you? If you answered "no" to any of these questions then you do not know these people hence you cannot trust their word. Very similar to my telling you that Chevy Cruz is an excellent car & that you should buy one. Would you go out & buy one? Why not? For the same reason you would not bank on these 2 amps sounding great. You would need to get around some (friends, dealers in your vicinity, dealers when you travel for business, audio shows, audio clubs,etc) & see if you can hear one or both to make up your own mind. Meanwhile you short list these 2 amps as "investigate further".