I swapped in an OTK 6n6 in the L10 pre yesterday. Not the one JP loaned me, I haven't tried that yet.
Sounded a bit different to the 'gold grid' but OK.
Listening today - I've settled in with the sound ... and I was losing the will to live. It's kind of drab and lacklustre.
Swapped back to the gold grid and the system is boogying again!