I had a similar experience with the SF Anthem line. I think system matching is the answer. In my case at the time I was looking to upgrade my preamp, so the Anthem was not a match. I have heard them (SF and Anthem) in systems where they sounded great!
Sonic Frontiers Preamps - Cold & thin?
In reading reviews on SF preamps, there seem to be two camps: those who think they are among the best tube units out there, & those who think they sound analytical, & thin in the midrange & treble. Would like to hear other's experiences & how they would rate them against AR & CJ. Also, how does the SFL-2 compare to the newer Line models?