Try the Sonic Euphoria that the dealer offers here on Agon, I think with a trial period too. It was sweeter then the Placette audio passiver preamp with better bass. With a passive you have to make sure it mates well with your amp. The SE was a real bargin when I tried it and I would have bought one if I did not already have a very expensive tube preamp that really was not much better, so try it for the price.
Happy Listening.
Happy Listening.