If I were to upgrade my 2 large yamaha bookshelf speakers that i got in a htibox deal to lets say, a pair of infinity primus 360's...is it really all going to make a huge difference in terms of sound quality. I already have a 12inch sub so I know I have enough bass. Im just more looking into the very warm and smooth mids and highs...
Tommy you maigh be able to upgrade those speakers with a set of 1977 Dodge 318 valve covers and hear an improvement. But the whole thing has to work together. I have a JVC boom box that sounds better in a room than a $1000 system that is poorly layed out. Very warm and smooth mids and highs are available in a lot of speakers, but can sound like yuck with a sloppy source. And, if the sub does not crossover at a higher point than most, you might have a big hole where it matters a lot. Synergy is an overused term for a reason.
The 360s need decent power to really sound their best; what's your receiver/amp? Bear in mind that with a few exceptions (HK and Marantz) most mass market receivers lie shamelessly about their wattage numbers.
Since you already have a decent sub, you really only need quality mids and highs. For the price of the Primus 360s you could get a much better quality bookshelf speaker. Max budget?