I finally pulled the E-6SN7’s from my amp and installed them into my preamp. What I was hearing before was influenced by tubes in the other stages. Now I hear the sonic signature of the Linlai’s more clearly.
First off, it’s an incredibly quiet tube. No noise or microphonics, I tapped on the PCB and nothing. There’s usually some sound from my NOS tubes. The bass doesn’t dig deep, I’m hearing a more pure sound than when it was in the amp. Highs are extended but not tipped up, no harshness. It’s neutral and there’s a good presentation of tonal colour plus a wide soundstage. The mids are linear and nothing special. Imaging is focused, but not 3D (and I’m using Melz 1578’s in my amp. I understand why they sound good in the Freya and Sachs preamps when used with a complimentary cathode follower.
The cost of the Global E-6SN7 is prohibitive for experimentation, it’s equal to a good pair of "NOS" tubes. Now I wonder if the Global HIFI (entry-level) tubes are worth a go.