Why are class A/B considered by many as "more musical" (whatever that really means) than class D amps? Is it a myth?
I don't know, some people might have made such claims, but not me. First of all, what is the definition of "more musical" and who defines it?
If you look it up on the Britannical Encyclopaedia:
Musical sound | Characteristics, Types, & Facts | Britannica
It says "
musical sound, any
tone with characteristics such as controlled
pitch and
timbre. The sounds are produced by instruments in which the periodic
vibrations can be controlled by the performer."
So in that sense, you would think that it is better to have an amp that just amplify the signal without altering the input signal's tone, pitch and timbre etc.
As Anthem said in their FAQ, the part I often would quote when people asked:
Frequently Asked Questions | Anthem® (anthemav.com)
Other manufacturers (McIntosh might be one) might have made somewhat similar statements, iirc...
Do the amps have a warm sound or a bright sound?
None of our components are designed with a "sonic flavor" other than playing exactly what's in a recording. Unfortunately with pop CD mastering, pushing levels way into overload regardless of how much distortion this adds is all too common. Recordings of acoustic instruments with minimal or no processing during mastering sound more natural, therefore they are a much better test of how natural-sounding the playback equipment is.
Or, if you just Google for warm sound, you might come across many different versions, and it may be difficult to find much about "musical sound", though it would seem obvious the two terms seem quite interchangeable in a lot of people's minds.
As an example, take a read of the AVS forum thread on this topic and you will see all kinds of opinions:
However, it does seem that to a lot of people, such as post#12 (the poster said he's a musician):
What is "warm sound" | AVS Forum
He said:
Typically "warm" means slightly rolled off (attenuated) high frequencies, with more emphasis on the mid-low frequencies
There isn't really a real definition that I am aware of, if you do, please share.
I don't think we can say that it is a myth, at least not without qualifications. If we qualify it by saying something like:
Amps that have specs and measurements that indicate transparency, such as evidence by having the following characteristics:
- Distortions and noise well below the threshold of audibility, example: -80 dB THD+N, full bandwidth, from 1 W to rated output.
- Frequency response within +/- 0.5 dB within the audio band 20 to 20,000 Hz.
- Very low output impedance, such that damping factor is >say, 50 in the audio band of 20 to 20,000 Hz.
- Cross talk between channels well below the threshold of audibility.
- Used for listening level that require power (preferably in terms of current) well below the amp's limits.
will sound different in that some will sound warm and musical, while others may sound crisp, bright, or even harsh, resulting in fatigue after a long session listening to music.
Then I would say such a claim may be considered a "myth".