Equalizer is your best bet, with everything else being the same. You can check the presets to see if there are already made equalizer preset like Dance, Rock, Electronica, Vocal, etc.
The other option is the quality of your media (music, videos). If your MP3 are 128kbps, you can see if there are better quality versions you can obtain from your supplier (iTunes, MS Store music, online resellers). Best MP3 quality is 320kbps.
You can also check to see if there are LOSSLESS versions of the songs you purchased such as ALAC, FLAC, AAC, OGG, etc. They are usually much better quality by at least 2x 3x the quality. Personally, I prefer FLAC since it's more open source. You will hear the individual instruments better, but not more 'powerful' sound. If the speakers sound tinny, they will still sound tinny. Just more clarity tinny.
Best bet is to get a decent pair of bookshelf speakers or set of computer speakers with subwoofer. They sky's the limit.