Tonjiru - water vs. dashi?

My recipe uses dashi, but the twice that I've made it before I had none and substituted chicken broth. Now I have dashi, and just looking around the web, some sites say when actually using pork (rather than a veggie-only version) dashi isn't necessary and to use water, because the pork and vegetables are enough flavor. It's not a huge deal, of course, but what are some of your thoughts?