lol I feel I ran into similar issue as you before. There is a difference between "sound quality" and "tonality". Sound quality I'm referring to technical stuff like separation, sound stage, detail......etc. But after all that there is still a tonality preference.

For example if you come from V-shaped headphone then chances neutral headphone will not satisfy your preference. Reddit has the tendency to suggest neutral headphone because it's the "audiophile" thing to do.

But often people forget people listen to what they like and some headphone will do better than others at different genre. So back to what you said, I don't think mid range is Sundara's strong suit, mid range master is like HD600 or HD650. You could.... as you said, fix it by running a tube amp. I'm currently using Lawton TH900 and running a tube amp to fix the mid range and recessed vocal LOL. Also as much as people say all dac sound the same, I find dacs have their sound too. Though you're already using Zen Dac V2 I think that one is already warm dac so you're probably ok. Maybe try a hybrid tube amp.

Don't feel afraid to try "fun" headphones if that's what you like. There are also high quality fun headphones out there. Though I don't listen to electronic or hip hop so I don't know what's the best headphone for those genre unfortunately. Maybeeeeee just maybe, see if you can find a TH-X00 Purpleheart for cheap to try.