I'm going to offer an alternative suggestion.
Before you splash out on new speakers and presumably lose a lor of cash selling on the Bronzes, I would invest some cash in your sources.
Your turntable is, by the reviews, a fairly good mid range deck. I don't know what cartridge you're using, but listen to the sound. If you feel there's something missing, then maybe a cartridge upgrade would help.
Next would be the interconnect cables between deck and amp, likewise the speaker cables. Doesn't matter how good the components are f they're strung together with doorbell wire, after all.
Now the big ticket item. The receiver. Consider upgrading that to something newer, and be sure to audition what you're thinking of buying, both with the speakers you've got and ones you might buy later. It would be a big mistake to buy an amp without doing otherwise.
Only when you've done all that would I consider changing the speakers. Most hi-fi buffs agree that you start with the sources, then move down the chain, finishing up with the speakers.
Oh. In a 10 x 15 room you're not really going to need that much power to achieve ear-bleeding sound levels, so don't be tempted by high wattage amps. Look for one with the sound you like and probably no more than 50 watts RMS per channel, high signal to noise ratio, or low total head distortion (THD), and a very good phono stage. You might even consider a valve based amplifier if your main medium is going to be those big black pizza shaped things... (said the guy who is a confirmed solid state electronics fan).