The Loki will probably give a couple more dB boost in the bass, yes. I haven’t heard it though so this is not a full blown endorsement.
Monkey wrench: are you settled on DT1990? You sound like a basshead (welcome to the club!). Similar in price to the 1990 is the Emu Teak. That will give you more bass from the headphone itself. You also have the option of a future Lawton mod, which if done right can give you stupifyingly good bass - quantity and quality. Alternatively, Focal Elegia are still floating around for 1990-ish money, maybe less. I know from experience Zen + Asgard + Elegia is also thunderous. If you’re not locked into the 1990, I’d give those serious consideration. In general, find the headphones that get you as close to your desired sound as possible on their own. Then get an electronics sound to bring that sound out even more.
Food for thought. Every option discussed here seems like it will be pretty awesome and I’m excited for you.