???Anyone Here UpGrade From Yaqin/Cayin/etc... To Another Tube Amp Considered Hi End???

While tubes do make a difference, the design is the key.  The BoX has well extended treble and a shocking amount of bass.  The Dueventi is more of what you'd expect from an el34, giving the richness with a smoother top and bottom end while still maintaining proper speed of the music.  Both excel at a holographic image and damn near black background due to the quality of the transformers.

I hope this doesn't come across as a disgruntled seller not closing a sale.  These amps will sell so I'm not worried about that. My only point is that not everything is cut and dry and understanding what a product is as a whole is much more difficult than looking at the 'key' components used.

With all that said, I've followed your journey here and I'm happy to see it continuing!

Congratulations on your purchase, but I do wish you had jumped on the BoX instead.  Yes, that is my inventory listed that you saw.  I am no longer the US distributor (mutually agreed decision) but their products are fantastic.  I probably would have directed you to the Dueventi more than the BoX with the 30.1 depending on your room.  The Dueventi is more romantic and doesn't need tubes rolled while also having a cleaner sound.  If you put a good set of NOS 12au7 in the BoX, you get a really incredible amplifier capable of driving most speakers.

I do wish you luck on the Icon though and hope it will take you to the next level!