Im a professional electronic music producer and The Corsair sp2500 is such a good system that I replaced my studio monitors with it. I needed something with a full bass response and subwoofer that was correctly integrated with a nice crossover and balanced for the sattelites. It truly is going to blow you away with how good it is and trust me the bass response is there! I use it in the default EQ settings for my studio work (really flat colorless response) but there are some great preset settings on it optimized for gaming and movies and music, you won't be disapointed.
Moving up from a Logitech system you'll be amazed, Logitech makes a good surround sound setup for cheap....but the quality of speakers and electronics is designed to give you "bang for your buck" instead of quality of sound. It's definately a big step up from that in the Corsair. It's obvious they wanted to take the market by storm with these because to get comparable quality you're gonna have to spend twice as much and get a 2.1 set of KRK Monitors and sub (I had enough set aside to get either one and still went with the corsair).