Years ago I had a soup & bread cookbook by Crescent Dragonwagon, and it was in that cookbook that I learned a few go to tricks for soup-making, one of which included adding soy sauce to a vegetable base (mirepoix; cajun holy trinity) is a tremendous way to up the flavor of a pot of soup. My favorite mushroom barley soup recipe came from that book.
Mirren, Magi or Kitchen Bouquet browning sauces (basically condensed root vegetables), Worcestershire Sauce, V8, demi glâce, freeze dried leeks or shallots and fortified wines can also be used (not all at once) like soy sauce to add a depth of flavor. Depending on the soup, liquid smoke is also a good one. If I need some acid, I won't usually do a vinegar but will do a dash of something tomato-y or wine. A bit of beer for chilli type of soups but usually beer is wrong as a flavor additive.
I think all bean soups need savory, sage or a bit of ground mustard.
I think all bean soups need savory, sage or a bit of ground mustard.