Hey simna,
To answer your two questions:
1) As I stated in my review when you go from the stock tube to something like the NOS CCA Siemens tube you get across the sonic board improvement (transparency, soundstaging/air around instruments, improved tonality/color density, dynamics and more liquidity/ease).
2) I use the term "organic" to mean that that piece of gear, or and overall system, sounds less like "mechanical/electric" device and more like the illusion of music. I also use the term "HiFi-ish" in the same breath, meaning it sounds like a great sound system, but not like natural music.
To answer your two questions:
1) As I stated in my review when you go from the stock tube to something like the NOS CCA Siemens tube you get across the sonic board improvement (transparency, soundstaging/air around instruments, improved tonality/color density, dynamics and more liquidity/ease).
2) I use the term "organic" to mean that that piece of gear, or and overall system, sounds less like "mechanical/electric" device and more like the illusion of music. I also use the term "HiFi-ish" in the same breath, meaning it sounds like a great sound system, but not like natural music.