From my experience, I've owned and audition over a dozen tube preamps and about 10 SS preamps. Not all tube preamps are created equal. You'll find that most the tube preamp had lower frequency roll off ( mid to low price range.) Some high end tube preamps goes deeper than SS preamp. i.e. The Audio Research SP 11 MK II, LS-5, SP-8 MK II ( not as deep as the rest on this list) and the vintage HK Citation I. Aside from the frequency extension, the tube preamps all sound much livelier compared to SS preamp. It adds more emotion to listening experience plus the tube preamp sounds more transparent than the SS preamp.