Likewise for replacement AC outlets, and even more so for replacement AC outlet cover plates that claim to improve audio quality.
Again, this would be easy for vendors to prove with hard science, but they never do.
Power conditioner vendors sometimes show an oscilloscope display of the power line noise before and after adding their product. But they never show the change at the output of the connected equipment, which, of course, is what really matters.
The last wire myth I’ll mention is the notion that boutique USB and HDMI cables avoid or reduce the degradation of audio (and video) compared to standard wires.
The signals these wires pass are digital, not analog, so the usual wire properties that can lose high frequencies don’t apply except in extreme cases.
For the most part, digital data either arrive at the other end intact or don’t. And many digital connections employ some type of error checking to verify the integrity of the received data.
So generally, if you hear any sound at all through a digital cable, you can be confident that nothing was lost or changed along the way.
Among devoted audiophiles, one of the most hotly debated topics is the notion that reproducing ultrasonic frequencies is necessary for high fidelity reproduction. But no human can hear much past 20 kHz, and few microphones respond to frequencies beyond that.
Even fewer loudspeakers can reproduce those high frequencies. If recording and reproducing ultrasonic frequencies were free, there’d be little reason to object.
But in this digital age, storing frequencies higher than necessary wastes memory, media space, and bandwidth. The DVD format accommodates frequencies up to 96 kHz, but then lossy (1) data compression, which is audibly degrading, is needed to make it fit! Record companies and equipment manufacturers were thrilled when we replaced all our old LPs and cassettes with CDs back in the 1980s and 1990s.
Now, with newer “high-resolution” audio formats, they’re trying hard to get us to buy all the same titles again, and new devices to play them, with the false promise of fidelity that exceeds CDs.
Another myth is the benefit of mechanical isolation. The claims have a remote basis in science but are exaggerated to suggest relevance where none is justified. If you ever owned a turntable, you know how sensitive it is to mechanical vibration.
Unless you walk lightly, the record might skip, and if you turn up the volume too high, you may hear a low-frequency feedback howl. A turntable is a mechanical device that relies on physical contact between the needle and the record’s surface.
But CDs and DVDs work on an entirely different principle that’s mostly immune to mechanical vibration. As a CD or DVD spins, the data are read into a memory buffer, and from there they’re sent to your receiver or headphones.
The next few seconds of music is already present in the player’s buffer, so if the transport is jostled enough to make the CD mis-track, the player sends its data stream from the buffer until the drive finds its place again. For this reason, large buffers were common on CD players sold to joggers before MP3 players took over.
Mechanical isolation is not useful for most other electronic gear either. However, mechanical isolation with loudspeakers is valid because they’re mechanical devices that vibrate as they work. When a speaker rests on a tabletop, the table may vibrate in sympathy and resonate.
Electronic devices that contain vacuum tubes can also be sensitive to vibration because tubes can become microphonic. If you tap a tube with a pencil while the amplifier is turned on, you might hear a noise similar to tapping a microphone. But microphonic tubes are excited mainly by sound waves in the air that strike the tube. Placing a tube amplifier on a cushion reduces only vibrations that arrive from the floor.