"Is our hearing not as sensitive to subbass frequencies at low volume?"
In a way, you're getting into what is called the Fletcher/Munson Curves. The "loudness" switches can't do a very good job at it do to the variations in LF performance in loudspeakers and amplifiers. William M. Leach addresses those "loudness" switches specifically in one paragraph in "Introduction to Electroacoustics and Audio Amplifier Design" 2nd ed. p. 8 citing those reasons. The basic idea isn't flawed, but in the end they turn into generic "bass boost" circuits.
"If so, how do you equalize this?"
Can't really. A fancy DSP system might stand a prayer.
"does this mean you necessarily will not get decent bass at low volume levels?"
Not necessarily, there's alot of other things that affect good bass or make it bad. Alot of people would probably be amazed how little bass their amps actually have even though they're still rated almost down to DC.
And room's acoustic/nodes will affect LF performance many more significant ways that also makes those buttons more-or-less insignifianct.
In a way, you're getting into what is called the Fletcher/Munson Curves. The "loudness" switches can't do a very good job at it do to the variations in LF performance in loudspeakers and amplifiers. William M. Leach addresses those "loudness" switches specifically in one paragraph in "Introduction to Electroacoustics and Audio Amplifier Design" 2nd ed. p. 8 citing those reasons. The basic idea isn't flawed, but in the end they turn into generic "bass boost" circuits.
"If so, how do you equalize this?"
Can't really. A fancy DSP system might stand a prayer.
"does this mean you necessarily will not get decent bass at low volume levels?"
Not necessarily, there's alot of other things that affect good bass or make it bad. Alot of people would probably be amazed how little bass their amps actually have even though they're still rated almost down to DC.
And room's acoustic/nodes will affect LF performance many more significant ways that also makes those buttons more-or-less insignifianct.