Don't know how hard it is to answer this question because it may be specific to this package, but hopefully some of you can answer. I now have Line 6's Podfarm software which works with my USB recording interface. It's cool in that you select your amp and cab and then drag and drop whatever effects you want in. The picture below shows an amp with a noise gate before and a compressor after the amp.
It is hard to see because I've tried to keep the image small, but you can see all the knobs on the head. The first 3 sections from left to right are drive, eq and volume. Then there are 2 knobs which are the "DI blend in" with the first one being the "Level" and the second being "Delay". These two knobs are on all of the bass amp models and (as usual

) the help files don't explain what these do. Can someone explain what these are actually doing? It certainly changes the sound, but it would be nice to know why.