This sounds very Blackstar like, very warm (I don't know if its because of the tube or not). That being said, I'm not sure that all the gain comes from the tube.
Compared to the previous models (the HT's):
- you can use your usual power supply (this pedal is very greedy though),
- the pots seem to be way more resistant,
- you got more options for the channel selection.
There are indeed four channel, but you can only select two. Also, there is only one eq for these two channels.