That is not a logical question. The answer is, "IT DEPENDS." If you have a ROOM that is not conducive to listening, it is YOUR ROOM, which is the MOST IMPORTANT ELEMENT of ANY system.
Once your room is set, you will, as many here have suggested, look at your weakest component. This is DIFFERENT for everyone at any given time.
If you wanted our shop to help you, we visited your room, made sure it was at least MINIMALLY conducive to listening (MANY factors here), and then we quizzed you on what type of music you typically listened to and how and why. Background music at a party is (obviously) different from dedicated listening to orchestral or opera or rock or whatever. Once we knew that, and the answer might be "every style of music," which is fine, we would look at what you had in your system and work from there.
The easiest thing to do, after making sure your room was good, was to put in our "best" hardware. Back then, and today, it would be Audio Research electronics and Magnepan speakers for the most accurate reproduction of most recorded music, which you know is heavily "tweaked" by various participants along the way.
If this did not work in your room for some reason, we might add a sub-woofer or go to a quality box speaker like, well, back then it was Fulton, but today, there are many (all of them tall, for some unknown reason-ha-ha) that may be accurate for boxes. We would probably keep the ARC electronics, but we sold many other brands, so sometimes this was a long process.
The point is, EVERYONE is different, so just throwing in the "best stuff" might not make YOU happy.
See? Not really a logical question. My advice: Find a good dealer and go from there. Most dealers of quality gear will approach your situation specifically. You could just need a pre-amp or a cartridge change, but one never knows until doing due diligence.
Cheers, and happy listening!