This request should be pretty simple to implement:

I would like an option to change the volume level indication (the text indication, i.e. "Volume: 50%" when you hover over the volume slider) to read in dB attenuation instead of percentage, such that it would read 0dB at maximum level, -infinity when muted, etc.

I don't know the inner workings, but I presume that this control already corresponds to actual volume, and not percentage of maximum output voltage from the sound card? Having a dB readout makes it much easier to reproduce desired levels when the output signal chain (and corresponding gain structure) is not always the same, since dB can simply be summed to arrive at total attentuation. A percent readout requires a bit of math each time the reproduction equipment changes.

sorry, amarok is not audacity

Although I'd love to see dB in volume bar, I imagine it's not as simple. Especially because volume goes through many layers before coming out from speakers. I have these:
1) Amarok volume (software)
2) Linux sound system (software)
3) External sound-card (hardware)
4) Active speakers aka amplifier (hardware)

Are 1 and 2 valid?

atrox wrote:Although I'd love to see dB in volume bar, I imagine it's not as simple. Especially because volume goes through many layers before coming out from speakers. I have these:
1) Amarok volume (software)
2) Linux sound system (software)
3) External sound-card (hardware)
4) Active speakers aka amplifier (hardware)

Are 1 and 2 valid?

That's absolutely true, yep.

It would be almost impossible to make the dB display precise. And without precision, there isn't much point in it anyway...