I have had good luck with JJ KT88's in my Sunn amps, I have them in a 2000S and a 200S with no issues. I would say they are a good "go to" tube, you pretty much know what you're getting and what they will do.
The hype for the new Genelex have intrigued me ever since I heard about them, and I've read reviews claiming outlandish performance akin to the original Gold Lions with out coming across any negative feedback. However, talk is cheap, and having first hand experience with
British Genelex tubes I didn't blindly buy into the new "holy grail" propaganda, but I haven't been able to find anybody that I actually
know that have tried a set.
Plus, they
look really cool, so I finally broke down and ponied up for a matched quad.
I got a push when a Reeves customer ordered a Custom 225 with Gold Lions as an upgrade. One of the guys at Reeves (who had discussed the new Genelex with me previously) called me and told me that they were ordering some matched quads from the distributor, and did I want to add on to the order.
JJ's are the factory KT88's in the Reeves, and I only have maybe 20 hrs on mine so the idea was that I break the Gold Lions in a little and then do some A/B comparisons. The bias held stable (last checked about 15 minutes before one red-plated
) and my initial opinion was that the tubes sounded great.
I've got a couple of gigs on them so far, and if they turn out to be the "second coming" I'll post about it.