No, that was my bad - the sensitivity is actually increased. The input signal required to produce the max rated output was reduced from +4dbu to 0dbu, but as i say thats actually an increase in sensitivity. Im not sure that makes it more valve like on its own - it wasnt the only tweeks (high and low Freq damping, and some other stuff was also changed), but it makes it react more like the reference VHT (not a goal in itself BUT the VHT is a very good and popular valve power amp) purely because that has a 0db input sensitivity.
When I first tried the XT800, I was trying to get the two amps to sound/behave as close as possible. Again not necessarily a final goal but my patches were tunes to the VHT. I found that EQ wise I could do that. It needed some changes but the VHT isnt flat - its flat for a valve amp but not flat - the Matrix is flat. What I was finding though was once I have tuned a patch to work on the Matrix it was great - then Id change guitar, of step on a boost and the two patches no longer responded the same. This was put down to the IP sensitivity. Basically as the signal strength changed, that extra gain or a change of PUs would cause, the two amps were reacting differently to it - because as a % of its required input the VHT was getting a greater increase. Its a small thing - but just helped get it close to the reference.
As I said it wasnt the only change, but the whole package is very nice.