Pro hardware compressor.
The Seventeen Xs MkII is a one channel transformer coupled compressor/limiter. It's a FET (field effect transistor) design that incorporate some new and exclusive features such as "High Pass Sidechain Filter", "Mix Knob" mix between dry and wet signal (parallel compression), "Signal High Pass and Low Pass Filters" that colors the sound nicely.
The 17Xs is Lindell Audio's take on the classic "1176 Sound". It can be smooth or it can be a rock'n'roll monster when using ratio 100:1 (all in). Beautifully constructed with exacting attention to both noise and musicality, this is the pro-level hardware compressor you have been looking for. You can scour the vintage shops and pay accordingly, or you can opt for Lindell.