As more limits are exposed, a pattern emerges until the speaker is no longer useful.
Speaker drivers are linear motors, they move back and forth. They also are asked to produce a range of frequecies called a bandwidth. Therefore, all speaker drivers require stroke within a designed/engineered bandwidth. This is affected by, but not limited to, inductance. The inductance, as it relates to the BL curve in reactance to the suspension compliance and resistance, alongside the physical limit of stroke of the motor and the physical mass of the moving parts, contributes to a maximum efficiency quotient within a given bandwidth, considering the motors ability to control temperature. It's crucial to highlight how this condition is universally present in every speaker driver on the planet; it is a balance of power, resisting forces versus acting forces. I have to acknowledge that we are glossing over direct discussion of Qes, Qms, and Qts.
What truly matters is how the aforementioned balance of power responds to the impedance curve, and this is related to how well the amp, the box, and the driver behave as an ecosystem, both above and below the impedance peak. Above the impedance peak, the driver will be power-limited, while below the impedance peak, the driver will be stroke-limited.
Do those two limits match each other in character? Where are the inefficiencies found while approaching said limits? How do they track with each other, and in what order do they appear? As more limits are exposed, a pattern emerges until the speaker is no longer useful.
Consider a car: if the engine is designed to limit before the chassis, you end up with a power-limited car. Conversely, if the chassis limits before the engine, it's a handling-limited car. However, a car with fully balanced engineering will have a engine, drivetrain, chassis, aerodynamics, and brakes that are designed to limit together at the exact same point, enabling it to handle, accelerate, stop, change direction, haul its payload, and more, all in perfect balance within itself and as each aspect is related to the other.
The significant difference lies in the fact that speakers do not convert petrol into forward or reverse movement. Instead, they react to invisible electrical impulses in an invisible magnetic field, changing direction, achieving multiple velocities, amplitudes, and frequencies all simultaneously within themselves and as they relate to each other. Furthermore, the transmission of this information is also invisible (via air), reacting and responding to the invisible acoustic nature of the room it's in or not in. Thus, what audio accomplishes within a few millimeters of stroke is vastly complex, extremely fast, and mostly invisible, aside from a bit of wiggling of the cone.
While I wouldn't categorize audio as an enigma, I would certainly label it as an advanced field of study. The key lies in understanding that none of audio is based on linearity except stroke and the desired end result. Everything listed in TS parameters modulates (changes) with amplitude (the difference between loud and quiet parts in a song or movie) to the; BL curve, impedance curve, efficiency curve, suspension compliance/resistance curve, and magnetic flux to tempurature curve. Many curves are at play, and they all relate to each other. Therefore, if a speaker is designed for linearity within a specific behavior, it may show limits earlier in other behaviors.
This is the affect and effect of audio physics. This is how a speaker works. Moving from this point forward, we developed LDLC and the Xmax stroke gurarantee, which allows one to actually see strict and minimal limits of allowable compression and harmonic distortion at maximum applied power levels. And this is what separates us from everyone else.