Interesting impressions. I'm hearing things a bit differently.
I crossed the 20hr threshold last night, and I find there to be a notable difference in microdetail between the RCA's and the JAN's. I'm hearing things clearly with the RCA's that I have to struggle to pick up with the JAN's. Separation, air and layering are better to my ear with the RCA's and they're more resolving.
I agree that the RCA's have a little bit less bass body than the JAN's (if pressed, I would describe them as being somewhere between the stock tubes and the JAN's in terms of body), but oddly I find the RCA's to have more bass slam/impact when called upon. I also question if the JAN's actually are blooming the lower-mids/upper-bass a bit, as I find the a general sense of greater clarity and transparency with the RCA's. With my Gungnir (which is already a pretty forward sounding DAC), the JAN's sound a tad wooly in comparison.
Honestly, I could see people preferring either presentation depending on their headphones, DAC and music selection. At the moment, I prefer the RCA's. That said, I have more tubes inbound for testing, so I don't know how long they'll stay on top.