https://upscaleaudio.com/products/primaluna-evo-200-tube-poweramp
How you build your "Forever" system. Do what this guy did.
One of the finest power amps in the world regardless of price. Learn all about the PrimaLuna EVO 200 Power Amplifier, a 50-lb beast with custom potted toroidal transformers, point-to-point wiring, and only the very finest components. In addition, with their stereo to mono switching, PrimaLunas power amps offer a logical and affordable upgrade path, making these a purchase of a lifetime.
Get a real amp, get a PrimaLuna.