Most mics seem to be bass light IMO. If you're some purest who deems EQ a mortal sin, you might consider mics with better low end? Otherwise I think the hint at having too much bass in your monitoring causing you to compensate by mixing the bass down might hold true.
My mics are little bass light. I've migrated towards a +3dB bump on the low end for those mics (contemplating a +2dB comprimise). Tapered gently down to +0dB at 5kHz. Which works well for me. But I've just got a simple audience perspective stereo setup. And I didn't start doing the EQ thing until I recorded a brass band, and it never quite sounded right / good to me. Until I bumped the low end. I kept going, that's not how it sounded live. It's an unfamiliar genre, but this sounds downright annoying to me. Bumping the low end smoothed it out for so it sounded semi-good. (I still need better mics with better low end, but still)
On the flip side, my soundcard tends to hype the low side. Which doesn't translate well. And if I play back the same track on my field recorder on the same signal chain, the basic EQ setup is completely different. So it might be your soundcard, and not your monitors or mics. 8" should be plenty for low end rumble. Unless you like to feel that low end. My BX8's which are considered worse than the 824's, are a bit bass hefty IMO. To the point of sounding muddy without high end converters (field recorder) to make it sound EQ'd okay. IMO. Not to say that it's not the monitors, but you might not solve the issue with a sub.