We don’t. One person’s preference doesn’t not define a label for everyone else.

Where’s the option for “My speakers don’t come with covers” ?

Most of Imagine Dragons music is intentionally compressed with “artistic intent”. Much the same way as some jazz singers will use microphones from the 1930s to get a specific tone.

Yeah it sounds horrible. It was the sound they were going for.

(New Electric wall outlets were ordered)

Oh that’s the problem right there. What is missing is money from your wallet you wasted on snakeoil.

Potential problems and solutions:

• Transformer winding has come loose due to poor manufacturing QC, does happen, need to get it fixed.
• Downstream component failing (failing capacitor can cause uneven current draw, as can failing diodes). Sometimes this problem is thermal related and changes with how long the amp has been on. Sometimes it’s load related. need to get it fixed.
• DC on the mains. Some designs are crap and don’t tolerate AC on the mains. If this is the issue the noise will vary with time of day and activity in the house (i.e. does it only hum while the wife is using her hair dryer on low?). Ideally throw out your garbage equipment and buy something designed by someone who understands how mains electricity works, or buy a DC blocker to work around their incompetence.

PC based volume control is almost universally done in 32bit. Windows will convert all incoming streams to 32f before mixing and converts the final result to whatever you specify in the audio settings. Most decent audio players work the same way. Quantization errors are virtually irrelevant. Do not underestimate how much dynamic range even crappy 16bits provide, even if done poorly it would be very hard to hear quantisation noise at any volume that would make me scared that my entire hifi would blow up if a Windows bug reset the volume control too high 😅

In some cases the digital volume control itself can be done within the DAC chips, or in receiver chips. Those are also almost universally done in 24bit or 32bit (though the latter in this case usually as integer mathematics rather than floating point).

On the flip side there are very VERY real downsides to analogue volume control, not the least of which are channel tracking errors, variable impedance mismatches and the requirement of additional components which add distortion.

Digital volume control is objectively the best way to do things now.

The Marantz Dbus thing is proprietary so unless someone has reverse engineered it you’re out of luck.

If you’re only interested in on/off your best option may be to wire up a rudimentary trigger to a GPIO port on the Raspberry Pi. Triggers are usually nothing more than a 12V output (though you’ll need to source the 12V from somewhere since the RPi runs on 5V).

Then you could use a product like this https://www.audiophonics.fr/en/diy-kits-and-boards/audiophonics-trigger-12v-230v-slave-power-supply-device-p-10661.html or trigger based power board to turn the amp power on/off.

You can get audio passthrough devices which detect an audio signal and make a 12V trigger as well if you don’t want to mess around with electronics. Then whenever you hit play on the hifiberry your amps will turn on without additional effort.

Or you could put it all on a powerboard connected to a RF controlled outlet, and everything on and off the same time with a remote.