What’s the best HiFi product of the last 20 years and why?

What’s the most important headphone of the last decade and why?

op is out here actually doing something

be the change that you want to see and actually post something

Marking the flair on this one Solved!. We did it, Reddit!

It’s really not so simple. The specs show:

< 0.35% at 20kHz, 135W, 8Ω load

< 0.04% at 1kHz, 135W, 8Ω load

Measuring at 20kHz, harmonics are ultrasonic and inaudible.

If you were to say the amplifier measures less than 0.04% THD at 1kHz into an 8 ohm load, most would think it’s excellent and inaudible.

PPM isn’t applicable for audio because there are no parts to count.

Generally speaking, THD is just the start of a larger discussion. It’s not a useful metric for listener preference.

Psychoacoustics is wildly subjective compared to the THD measurements.

Dr. Earl Gedees wrote about this in Premium Home Theater, 4.1.b (pg 58) which claims:

There is virtually no correlation between Total Harmonic Distortion (THD) or Intermodulation Distortion (IMD) measurements of a system and the subjective impression of the sound quality of that system. The correlations were weak, but most shockingly they were negative—according to these tests people liked THD distortion. This is actually somewhat true in general that people prefer some forms of distortion to no distortion.

What The [THD] Specs Don’t Tell You… And Why is a great video from RMAF 2015 from Audio Precision. The presenter demonstrates different types of distortion and shows just how inaudible or audible it can be.

Take this pre-amplifier comparison for example. The OP could reliably ABX the Conrad Johnson tube from the Benchmark solid state and preferred the one with arguably higher distortion.

This second vs third harmonic distortion test concluded that tracks with second harmonic distortion were preferred in about 75% of cases; 25% those of the third; surprisingly never the original tracks.

Have a look at this blind test of distortion. A second harmonic of 0.02% THD is weakly preferred over 0.0000002% THD in nearly every case.

Bob Katz also built a harmonic generator to test his preference as well - read about it here. Their preference? Added second harmonic distortion between -60dBFS (0.1%THD) and -66dBFS (0.050% THD).