Soundproofing around water softener
Sound isolation is sound isolation. Lower frequencies (bass) are harder than higher frequencies (treble) to block, but anything helps. If you have the space, a purpose built wall with staggered studs (so each stud only has one wall surface connected to it) packed with insulation is good. You can add as much of whatever other product you care to onto that (resilent channel as well as the other products you have mentioned already) but if you start there, you are fighting less as you have a good isolated base construction - many of the &quot;products&quot; are more of a band-aid on top of a wall structure that was not built from the ground up for isolation.
&quot;Open concept to basement&quot; sounds like a firetrap waiting to happen - I'd want to get your utilities behind a couple of layers of Type X drywall and rockwool and a well sealed firedoor just for the fire rating, and consider the sound reduction as a pleasant side effect. Let the children you want to have live to adulthood.