Simple acoustical solution first. Install th speakers woofer out closer to the room corners. This changes the loading from a half space to.a quarter space and provides an immediate 3dB increase in bass. Avoid spacing that are related to the woofer height, so if you woofer is 24" off the floor, avoid 24" or 48" from the rear or side walls, as those will exaggerate resonance in the 125 and 250Hz range.
Your speakers cross over at 200Hz to the mids, so you should be able to avoid too much 'thickening', chestyness, or muddiness on vocals.
Room treatments are great but have little effect undr 200Hz. Just look at the published absorption curves for 1" and 2" panels.
When you're satisfied you've optimized speaker placement, next would be the other mechanical transducer - your phon cart and arm. If your cart is a low compliance MC in a low mass arm, the cart/arm resonance will be too high and 'the tail wags the dog' - the stylus and cantilever just shove the arm around so you lose bass. Optimizing the mass and compliance allows the stylus and cantilever to move against the mass of the arm and bass improves dramatically. Go too far, and tracking, especially warped vinyl, suffers.
After that, tweak away, but don't expect miracles.
Finally, a subwoofer or new speakers that can move more LF air, e.g. 2-8" woofers are other options, or acquiring an amp with Dirac room equalization.
But most of all enjoy the music, and enjoy the journey.
