Am wanting to find a preamp for my GS412. I have narrowed it down to these three preamps....Either the Eden Navigator, the Ampeg SVP Pro, or the Aguilar DB659. I am somewhat confused on the Ampeg though....whats the difference between the SVP Pro and SVP CL?? Anyways, let me know what your thoughts are on these amps if you have experience with them. Thanks guys....and gals.