So the Oriolus BA300S tube amp for the 1Z is in the house and under testing with the Solaris.
I'll add this in the review when I have had enough time with it but after an hour with it I can say the Solaris scale well and, the very interesting point is that it takes the Solaris a few notches up on the bass... what I did miss with the 1Z alone I don't anymore with the BA300S, the mid bass kick I was missing is here and the best part is that it's without loosing anything in terms of textures and layering quite the contrary
I think this small tube amp would pair so very well with the ZX300 as it's the same form factor, making it a potential killer combo for the price.
On monday, I'll get the 8 wire Hansound Zen and then I am set!
I am kind of skeptical that a $350 amp adds fidelity to a $3K DAP. Perhaps it is just adding tube coloration (distortion). You may want to check out the Cayin N8 as an upgrade from 1Z if you like that type of sound, seems more convenient than chaining two devices.