For those getting this for its tube sound, go away. It isn't tubby or warm at all. The AMP is very transparent, if you keep the stock tube it is slightly warm but sounds bad, specially if you rise the volume.
I got an A90 and the A90 sounded way better, until I got the Genalex E88C/6922 tube everyone is talking about. At first I wasn't sure to buy the tube, but I decided to buy it. Now when I compare my A90 to this amp it sounds really close. Unless I rise the volume way up, I can't tell the differences, except the CTH has a slightly warmer bass and the sound isn't as open. But the topping costs twice, and the sound isn't twice as good. At least my ears can't hear it that way.
Then the SDAC isn't on pair with the AMP from my point of view, before having a D90 I used to have schiit modi multibit, and even that sounded better than de SDAC using USB as input.
I tried a couple of full sized headphones and some iems. The iems sound bad, at least with the stock tube, I still have to check how it sounds with the new tube.
Conclusion
The amp is very worth it's price, instead of getting the combo get a better DAC like a schiit.
If you want to upgrade from here get a genalex tube.
If I had upgraded the tube before and had had the opportunity to test the topping A90, I wouldn't had buy the topping. I would probably had bought something warm, like class A amp.
DACs: SDAC, Schiit Modi Multibit + Schiit Eitr, Topping D90
AMPs: CTH, A90
Tubes: Electro-Harmonix 6922(stock), Genalex Gold Lion 6922
Headphones: Focal Clear, Hifiman Arya, Dunu Falcon C
DynawayI read somewherre amperex are warm.
Since I already have the A90 I'm looking for something that makes the cth sound warmer, do you think this is warmer than the others?