Hi Bbro. The JOR has KT90s. I haven't heard it with different tubes, but some other Audiogoners actually prefer the KT88s or even EL34s as they found the midrange sweeter. The midrange with the KT90s is sweet enough for me - it sounds very natural.
I've written more about the JOR in the review section. I'm not sure there are too many conventional speakers with a sensitivity better than the CUBs (94dB) - the Sophias are 89dB - but I can imagine the 4Ohm, or less, load does not help.
I'd just be aware that if you like loud, as in realistic, solo piano, then you will have problems with clipping.
In genernal, the bass punch is acceptable, but not ideal - I hooked up the old ARC D125/SP9MkIII the other day, with the StormIII too, and this really was much tighter and dramatic - there were losses elsewhere, but they were minimal: a little more grain in the upper frequencies, really only noticeable when listening to the string section of an orchestra; a slightly denser sound, which, who knows, could be preferable for some listeners.
I suppose, for me, the most amazing thing is that the JOR even comes close in the bass, and actually exceeds the ARCs in other areas - in Australia the JOR costs $4,200Aus, while the D125 was $10,500 in 1990; and the SP9MkIII close to $6,000 in 1996 - a VS110 is now $9,200.
Still, it's not a bargain if it doesn't suit your listening tastes, so a home audition (as usual) would be nice.
The JOR has developed a hum from the power transformer in the past week. It's not very loud, but certainly was not there before. I've started another thread about reliability problems in amps too.
Cheers, Rob.