The specs you quoted are from the Berning website, and are the typical David Berning conservative type specs, which he always shows "worst case" types of figures. The distortion figures are at clipping for that amp. It is stated that the figures are lower at more normal outputs.
In addition, nearly all the distortion is located at the 2nd harmonic, which is where we want it to be when using the single-driver loudspeakers that this type of amp is designed to typically drive. For more info on this, see Eduardo DeLima's article "Why Single Ended Amplifiers?" on the web. This is an article with detailed test info which shows the complementary relationships between single driver loudspeakers and single-ended amplifiers, with both showing harmonic distortion profiles predominating at the 2nd harmonic. In both theory and testing, it was shown that this complementary relationship will cause the self-cancellation of some(and in most cases the majority) or all the THD in the AMP/SPEAKER combination. It shows the folly of attempting to extrapolate any meaning from single component distortion specifications, when these may not hold true when exhibited in a system context. True, most other systems with wide spectrum harmonic distortion profiles(solid state) are purely additive in distortion, due to their harmonic distortion being all over the place. But in this case, the THD is not purely additive between these types of components, and in fact is subtractive in most cases, and even totally self-cancelling in the most perfect case(not likely). So it is concievable, and shown to be proven by this article, that the case of single-ended amp and single driver speaker have a unique relationship that can actually cause the SYSTEM to have a measureably and audibly lower distortion than ANY other type of amp/speaker system regardless of technology or cost.
This is where the spec game is totally lost. Nobody measures system distortion, only individual component distortion. They see half the info, and try to make definitive statements. This is also why I urge listening testing.
I have fought this "spec battle" for over 20 years, and there is always someone who "knows it all" because he looked at some scope trace, or read some spec sheet, or rides a test bench, and thinks what he learned from that is applicable to audio. The specs are a trap. They are a trap that stops people from learning the full truth. A marketing ploy.
The "scientific minded" people are the first to fall into this trap. They are numbers minded, and get suckered right in. They use the specs to "show why this can't be so". It's a magic show. They aren't showing you everything. They are showing you just enough to make you think their way.
I have written this type of post numerous times on this forum. And there is always another person coming along with the spec argument. You cannot rely on any spec, except maybe 120VAC 60Hz input. They are measured in an "out of context" testing regime, and mean nothing in regard to how they perform in a system context. To place a big trust in these specs will lead you down the primrose path to poor sound.
Maybe I sound harsh, but I am really trying to be helpful and informative. I didn't fall off the turnip truck yesterday. I know all about testing methodology, meters and scopes, what they do and what they don't do. I was once a "spec believer". Then I woke up, when somebody showed me the flaw in it. Now I'm doing the same for others. Some won't listen.
