Of course if we accept the kii was limited ( it’s just a bookshelf after all) from the start and really needed a add on like this to deliver a ‘full’ sound my attitude ‘might’ be different. That simply is not what we were told ( repeatedly).
Engineers know that 90% of effort is spent in solving the problems that occur in only a fraction of cases. I'm quite prepared to believe that the Kii Three is capable of most domestic duties without problems, and yes, because of its modernness, cleverness and energy inefficiency, it can behave like a big box.
But I think in the professional situation, listening at insane SPLs for long periods, it is probably going to go into bass limiting unless extra grunt is provided - everything's going to get hot. It won't shut down or get damaged though - and this is why Kii might feel justified in selling the speaker on the basis of its 'big box' capabilities. In most situations it's true.
This is the modern world: dynamic systems that don't have a fixed specification, because they're capable of adapting rather than burning out. Most people won't even register the difference. How do you advertise that feature in a way that 'old school' audiophiles understand? People need to get with the modern world!
The BXT add-on is just for professionals or perfectionists - and also improves dispersion in the vertical plane I think.
