Preface: i use a minidsp nano Digi as a crossover.it has digital inputs and outputs and internal volume control. but when I use digital volume control (windows, in-game, Spotify) I get bit loss, the fix is analog volume control. they are easy to find until you want to add a subwoofer
the Coleman SR5.1Mk2:
it’s a 5.1 volume controller that’s 6 individual channels on one knob and that’s it and boy is it great. You do not need this unless you have 2 or 3 balanced dacs dacs and a subwoofer.
the Colemen stack:
one little bear xlr speaker switcher
3x nobsound ns-o5p xlr volume control for fine-tuning levels
edit 1 i use the speaker switcher to switch between my studio monitors