Well, I have a focusrite saffire pro 40 that just last week I recorded my bands ever evolving catalog of EP songs on and I feel that the pre's on the unit are fine but the vocals need a little something extra for our next set of recording and rerecording. I pretty much only have a $500 budget for a single channel good sounding preamp and from what I've read everyone says the ISA One is great. So my question is... does anyone have any experience with it and can tell me if its worth the upgrade please. Also, hows the D.I. channel on it? Thanks!!!!!!!!!!!!