The Mullards are great - all the usual adjectives apply like "liquid, smooth" and so forth. I think they're also more clear and give deeper bass. The thing I like best is that there's a greater difference between stock and Mullards when running the amp in SET mode than in P-P...the stockers sounded overly "tubey" to me in triode, with thick overblown bass, but the Mullards are just awesome in triode: clear with deep but nicely defined bass - really wonderful overall. Two caveats. One, I'm using Tesla ECC803S tubes in the 12AX7 positions (they are alleged to have been made with TFK tooling) that are very, very clear...so much so that at first I thought they were cool and hard-sounding in P-P. I'd have to guess they help give a kind of shimmering clarity in concert with the Mullards in triode. Second, as always, these results are speaker- and system-dependent and YMMV.