So I did a bit more research and plenty of looking....
Scenario
What is the best suited and most affordable amp we can find for powering Buttkickers? As Behringers NXD series seems rather expensive in USA or other regions (is good price in UK) what can we find as an alternative.
Buttkicker 4ohm models.
BK Mini
BK Advance
BK LFE
Also with good controls and an amp that supports 300watt but importantly also features not just a fixed but
manually adjustable crossover from 40Hz-300Hz. Using a mild -12dB slope of bass attenuation.
I believe this is a great option from Douk Audio (Nobsound) with excellent features
* Using TPA3255D2 amp chip equipped with 32V/5A large power supply, is enough to drive 320W subs/speakers
Nobsound G2PRO
Easily available worldwide on Amazon or Ebay the price is rather amazing too.
Amazon UK
Amazon.com
It will certainly power the medium sized BK Advance okay and I still think as Shakeit has a high energy output we may find it also okay for the largest BK LFE units. This would need to be tested and confirmed.