I seem to recall an EQ that had an integrated spectrum analyzer.
So, you slap an instance on your bass guitar and one on your kick, find the fundamental of your kick via the analyzer and neaten up the surrounding area and accentuate the fundamental or the harmonics of the fundamental, then move to the bass guitar and track the moving fundamental of that part. Then try to accentuate or cut to have the two work together nicely. Etc.Where's that harshness on that Tele? What's the woof? B3 or Piano? Is that boxy from the kick or the Les Paul?
Yes, I do all this in other ways (ears mostly and eyes) but I know I'd love the potential of an integrated plugin.
Who makes an EQ w/spectrum analyzer? RTAS / AAX