Howdy, I'm looking at getting a new bass. i currently play 2 ibby sr's, and love them both, and am wanting to go to something more heavy. i'd love to stay with ibanez, and you can get the srx's on pretty good deals. can anyone enlighten me to the difference between the srx 550, 520 (basswood bodies), and then the srx 690. i've been doing some searches but cant really find much information. Thanks in advance!