Diagnosing inadequate bass in an audio system.

Try this.

Excellent question which I think most don't understand.  

So do you want accurate bass or the exaggerated bass that is so often provided in cheap sound systems, car audio, etc.  

Most high end (accurate) systems will be judged to have inferior bass compared to a lot of consumer systems.

Jerry

There are test discs with consecutive tracks with different test tone frequencies that go all the way down to 20Hz.  Get one and see where you start to detect a falloff in output.  More scientifically, you could see how they do with a SPL meter.  All that being said, yes, a ruler flat response all the way down to 20Hz, while also being very, very unlikely, may also not sound "realistic", whatever that means.

Get a loudness control.

A likely problem is your seating position is in a null point.

The following explains the mechanics of bass in a room. While the subject is subwoofers… it explains standing waves and will give you lots of info on how the room changes the characteristics of bass,

Also, it would be helpful to know your components and the venue. There is a place to put photos and your components under your UserID. This would allow us to understand your situation and be an order of magnitude more helpful. My systems are shown.