Out of curiosity, why GS wavetable? Thats why you are getting different sounds, and thats what you use when you have nothing else, its horrible. That aside how are you hearing this, with outpit set to GS? Maybe try HD audio device(speakers), I am just confused about the output, and use of wavetable, isn't there Studio Instruments Bass that you could use for bass, thats what the controller is for, controlling softsynths, and other things as well. try inserting the Bass from SI, and use your 25 as input but change output, maybe, like I said I am confused. Good luck, try reading on how to use softsynths, stay away from the wavetable!