I don't have the 350, so can't help out there, but I find that I do NOT adjust the amp level on my sub much at all. I have the sub turned up a little more than my wife would like, and so I think that it is at a level that is a little louder than some. I do notice that movies that are mixed nicely have more bass than anything else I listen to, but I don't find anything "missing" for those that don't have high amounts of bass.
PS. I think that my father-in-law patented white-out for use as a "level indicator" for audio dials years ago.
