Parallel input stage idea - 1/2 12AX7 ll LND150 ?

[Stephenl]

I was thinking of trying this, but I don't have a lot of experience using FETs. I'd like to try the conventional arrangement of common Anode and Cathode resistors...but I'm guessing the LND150 will need something different for biasing.

Thanks in advance for any education on this.

[J M Fahey]

They are very different, biasing will drive you crazy.
I would build 2 independent gain stages, each biased properly, join inputs and use a couple mixing resistors to mix outputs, say 2 x 100k or 220k.
Or use a 500k linear "blend"  pot and you can pan from one to the other or get both same level when set to the middle.