The DIY route to achieving this design is enabling a method that allows permanent access to the selected Amps, as the Speaker Cabinet is designed to have a recess to house the Amp, with the Amp's fascia flush-finished to the cabinet. An OB baffle can have an enclosure made to house the Amp; this can be placed local to the Speaker or mounted on the rear of the Baffle.
Many Amp producers who supply an Amp for this role are keen to offer a 2-year warranty, which pretty much shows great confidence in the reliability of their product.
A DIY build does not mean that one does it themselves; it can also mean that the support of others more adept in Cabinet Making and electronics can be commissioned to assist.
Buying off the shelf is doing much of the same, but a Turnkey product has a premium in the costing, if compared to a design produced using similar quality material and electronic parts.
Buying off the shelf does enable a pre-purchase demo if it is able to be arranged? Does enable user reviews to be read, if a review is able to be found?
The Link shows a full conversion Active of a Speaker produced by Troels Graveson that is a Passive/Hybrid design.
https://www.stereonet.com/forums/topic/573796-troels-gravesen-3wc-15-active-version/

