I have found that the idea of speakers sounding their best at low volume level depends on the amplifier as much as it does on the speaker. This is regardless of Fletcher Munson or relative volume of frequency adjustments.
For example class D amplifiers tend to require higher volumes to come alive in the bass regardless of speakers.
Class A amplifiers tend to do the best job at lower volume levels as do robust Class A-B designs that are stable to very low impedances.
That said there are speakers that do a better job too- mainly higher efficiency designs 89db and higher including your Tektons.
Your Tekton speakers should be capable of quality low volume listening and if they do not, look to your amplifier as the reason.