Read it again. This time slowly and carefully. Glancing what someone has written assuming it's wrong is just jumping to conclusions.
These factual assertions can be backed up with real-life experiences. Visiting warehouses and production facilities. Talking to employees who work in wiring stations at consumer/professional electronics companies. Talking to quality control departments, electrical engineers who are working in the field; not just academics/earned degrees, and ultimately rationalizing that as with all industries there exists variation due to customer demands and targeting specific segments of that market. Audiophiles, audio professionals, and the occasional music enjoyer may have very different priorities about what good sound is to them. Everyone's different. So is the gear. The term "audibly transparent" has been thrown around far too much over the years. If an amplifier + source component is truly accurate, then you will easily be able to decipher differences in sound where one track could be virtually unlistenable due to excessive compression and limiting - shrinking soundstage and collapsing micro-dynamics and transients. Everything on a system that isn't resolving might sound "clean" but rather one or two dimensional. And imaging, which we all know is the illusion of a sense of space or locale in a recording (especially live recordings) is not so easily replicated just because an amplifier or DAC has high SINAD and low THD.
I'm actually sorry for being a bit overbearing. So I will try to explain myself a bit better. Parts do matter. You can say they don't, but they most certainly are the most important thing in all electronics; not just audio equipment. Remember - we are modulating electricity and reproducing sound through stored energy and drivers that have physical mass. The application of parts and furthermore the circuit design which these parts are centered around matter a lot.
Here is a bunch of solid info... research each of the points I've made if you care to.
Small surface-mount capacitors and cost-driven switching power supplies exhibit higher ESR than large radial electrolytic capacitors that are interconnected via metal or copper bus bars. The same principle applies to power supplies: dedicated EI or toroidal transformers generally provide superior current delivery and stability compared to inexpensive switch-mode designs. This trend can be seen across HVAC and military, for example. They commonly use what is more reliable and performant in the long term. The electrical characteristics of such parts can be contrasted very easily. It's rather obvious.
Capacitors rated at 85 °C versus 105 °C are not inherently inferior; in certain DAC output stages or analog circuits, 85 °C parts may actually be more appropriate to the design goals and, in some cases, even more expensive due to material choices or manufacturing processes. It's not just the higher number that counts. Material science can tell us plenty about long term reliability. Film capacitors and those made for an intended purpose (custom or otherwise) typically have very have low dielectric absorption, which also impacts sound quality. I could go on... but just research -->the measured metrics of capacitors that determine their behavior and reliability when used in electronics such as audio equipment, and why this matters for sound quality.
The use of off the shelf/inexpensive operational amplifiers instead of fully discrete transistor stages is often a shortcut employed in budget audio equipment. While op-amps can achieve excellent bench measurements, these measurements are typically obtained under ideal, resistive test conditions and are designed to be easily repeatable for marketing purposes. Sound familiar? Go to any of those budget gear websites and you will be bombarded with charts and graphics with high numbers... higher than you will ever need. Such data does not reliably translate to real-world performance with reactive loads, such as loudspeakers or demanding headphones. Of course, such manufacturers are aware of this.
Even advanced test methods, including multi-tone testing, remain relatively “safe” and do not stress an amplifier or DAC in the same way real transducers do. In practical listening scenarios, driver behavior in passive speakers, headphones, and even active speakers varies significantly depending on how the amplifier modulates current, manages stored energy, and delivers that energy cleanly and consistently to the driver. For example, in headphone amplifiers that are not truly performant, the voice coil is driven with more authority than the entire driver itself, which leads to smaller amounts of air pressure being created, and therefore sound waves that do not encompass what that speaker/headphone is truly capable of. This is directly related to how the capacitors are wired to the power transformer, and the sum of ESR/ESL along with the slew rate and rise time and damping factor which all, to a large degree, get to decide how linear and accurate the pistonic motion of driver unit(s) can be in real-world listening and professional applications, such as audio production and mastering.
Experienced listeners who have spent extensive time with different headphones, speakers, amplifiers, and source components recognize that these electrical and mechanical interactions are fundamental to perceived sound quality—and cannot be fully captured by laboratory measurements alone.
And yes, I wrote all of the above by myself because these are facts I've known for at least the last decade. It's not just the measurements - it's how we got there that counts. That's all I'm saying. Peace and happy listening.