A few words about Cayin and this item (which I'm interested in).
I am impressed by Cayin products. I had a HA1A headphone amp which was very good for the price (and was improved with valve rolling, capacitor upgrades and hard wiring it to triode mode to remove the long wires to grid 2 which pick up noise).
I still have a CD100i cd player which was very decent and good value; with cap upgrades to the valve board, Tent clock mode and top quality valves it is amazing; in the £4000 class, and has impressed a very fussy friend.
I build quite a lot of valve gear; to just make something work isn't easy; to get good sound takes more effort; but to do so in a way suitable for volume production and at an affordable price takes a whole lot of doing, and Cayin do this very well and I appreciate this.
Now a tekky comment on the N3Pro. The valve is used as an output buffer using the cathode follower cct. This cct gets a degree of criticism, but I think this may be due to generally using ECC82 valve for high GM (gets output impedance low), but has low gain.
Even thought this cct has no gain, gain does have a benefit as the 'error' between input and output is roughly proportional to 1/gain; the higher the gain, the better. ECC81 can make a good cathode follower (I have 2 units with this).
Now pentodes, in pentode mode, make very good cathode followers (I use this),as the voltage gain is very high indeed. Ultralinear mode on the N3Pro is a flavour of pentode mode, which is why it works well - as many people here testify to; it is the favourite mode of the majority, I believe.
But I can understand that triode mode can work well to give a different flavour, perhaps not as accurate but pleasant all the same.
I'm close to ordering one.