Let me explain a little bit about distortions. THD (Total Harmonic Distortions) mean a sum of harmonics caused by distortions of very clean sinusoidal signal. Traditionally power amps were characterized by maximal power when distortions reach 5 or 10 percent. It does not mean that at 1/10 of output power distortions would be 5 or 10 percents. They can be a fraction of a percent. What actually matter, how the amp behaves dynamically. Our hearing is dynamic. We hear sounds that are a sum of loud bass, cymbals that decay, and subtle reverberation caused by reflections of sounds from walls. And we spot any distortions that change in dynamics. It does not mean that we hear distorted sound. Rather, we experience loss of clarity, 3-d soundstage, warmth, air, the sound as if is clean, but it does not sound natural, and causes fatigue pretty fast. People knowing that such amps have very low THD level prefer to call such distortions "Analytical sound", or even "Clinical sound", "Dry sound", "Cold sound". Do we really need some 2'nd order distortions to get warm, pleasant, airy sound? The answer is, no. The lower are distortions, the better is the sound. The key is, how the amp distorts while the power changes. When sounds decay. On peak loudness our hearing forgives pretty high THD, with wide spectrum of distortions. But when sounds decay, distortions must go down and only down, their spectrum must go narrower and narrower, until 2'nd order only distortion remains and decays before the sound itself decays below the noise level. My explanation of this phenomenon is, distortions of amps are inaudible when in dynamics they mimic distortions caused by physical media, including our own eardrums. They simply hide behind them, because our hearing are adjusted to ignore them, either by God, or by evolution. Once again, low THD itself does not matter, what matters, dependence of distortions on the signal level; how quiet reverberation, whispers, ride on top of louder sounds, and how low are distortions on the subtle sounds, how the amp preserves reverberation that bears the information about the environment. How low is THD on the maximal power does not matter if when sounds decay spectrum of distortions gets wider. What matters, decreasing order of distortions when sound decays, and how the sound envelope of the signal changes the signal itself.
@@downnoutdubin - THD is very old and obsolete measurement that today is still used for marketing purposes. Even engineers are being taught to design for low THD, instead of designing for low audible distortions. When they mention "Our amp is very clean, it has 0.01 percent of harmonic distortions"measured at say full 2W headphone output it does not mean that it sounds cleaner than another amp that measures the same 0.01 percent on 1/10th of max power, 0.02W in this case, if the first amp is class AB amp and has 3'rd, 5'th, 7'th harmonics summing 0.03% at 0.02W, while the second one has 0.01% of 2'nd order harmonic at the same low power, being a single ended tube amp. When you test amps, feed very clean sinusoidal signal, and observe the spectrum of distortions. Real high end amp does not show distortions on very low signal level. When you increase the level, you may see the 2'nd distortion appear and increase with the increase o the signal level, then 3'rd harmonic appears, while the 2'nd one dominates. More power, higher order harmonics are visible. However, the lower is their level, the better. But if in dynamics increasing of signal level increases distortions the way close to how your own eardrums distort, such distortions are inaudible. Contrary, if another amp shows wider spectrum of harmonics on very low signal levels, but on full power their total sum is say 0.01%, such an amp would not sound better. We expect the sound getting softer when decay, not vice verse. We forgive more distortions when sounds are loud, but when it decays, we expect them to go down, and only down. However, it seems good for an amp to run cooler, dissipate less power, consume less power. Class AB amp is the way to save electricity, get you amp smaller, lighter, colder. You may cheat decreasing THD on full power by a negative feedback, but if you want an ultimate sound quality, you have to burn electricity. No other way. It does not mean that negative feedback is bad. It is a good tool. What is bad, is cheating applying tons of negative feedback to sweep THD under the rug. What I was talking about, is harmonic distortions only. There are other factors except them that are needed to be considered if you want a state of the art sound quality.
I have a Woo Audio WA6 2nd gen, and a Burson Soloist 3x GT, which is outputting very high voltage , but I prefer T1 with Topping A90D..... The dac Is Matrix Element X2 , from a Matrix SPDIF 2 (reclocking from my Mac mini M1), charged through an iFI GND Defender and a Supa Nova cable from iFi . I think is also about attack and decay , not just about detail . At least for me . I will go for the Echo amp .Great video !
I wish I could find a good video or on-line instructions on how to connect a headphone amp to an integrated amp. Can someone explain this in layman's terms, please.
