Pardon me, but I am confused. You say you are looking for another regular or SE+ Line 3, and then you say that it did not sound very good. Then you proceed to mention looking at preamps from VAC and VTL. I really don't have any idea what direction you are heading in, do you?
VAC is worlds ahead of any Sonic Frontier gear I've ever heard. I don't know what your budget is, but there are varying prices of different VAC preamps too. Patience is a virtue. While I do prefer VAC over many of the standard competitors, you may find a nice value in a Shindo, Herron, Messenger, or other manufacturer.