Hypex Electronics is a Dutch company that produces amplifiers, power supplies and DSPs in the highest possible quality. They are used for modern high-end audio applications.
Specialized in active modules and switching power supplies. It offers several kits (such as the NC400 kit) and modules. The quality in our opinion is audiophile .
While not in absolute value cheap we can guarantee that these are extremely well sounding and truly reliable products
There are also flush-mounted amplifiers with up to 3-way programmable crossover. All via USB with additional digital inputs
All that remains is to try them!