I do not have a book on this preamp but will try to find one sooner or later.
@billpete , if you go to Cary Direct’s site, you may be able to find a manual to download. It might take some screwing around and navigating if they are not showing a SLP-98 that you can click on, but if all else fails, I am about 99.9% sure that if you call them on the ph and speak to the sales dept (they will actually talk to you on the ph if you want to buy something) they would sell you one.
It slipped my mind when I posted that you were inquiring about the 6sn7s. I recall that on a 6sn7 thread that a member, @mulveling , had some good things to say about the re-issued TungSol 6sn7. I am not trying to start a separate discussion or argument, but the only reason I have not tried them is a personal one. Again, not that my ’05 experience is applicable, mine came with EHs and it was still a better sounding pre than my SLP-90 was with more expensive 12AU7s. As I am pretty sure I have already mentioned on one of these threads, I am running with a pair of vintage 6sn7s (or variants) for my balanced inputs (one of the differences in our preamps) and am combining that with four more JJ 6sn7s in the other slots and I THOUGHT at the time after I made the switch that I liked the JJs better than the EHs, but that may have been because I WANTED it to sound better. Regardless, as I think I have also previously typed on one of these ’98 threads, a quad of better, probably vintage, 6sn7s is on my short list.