Further to @Ingolf comments as almost nothing has really changed, I did a small test. In theory Ingolf is totally right, and he is also right about the facts that profiling skills have improved also, and the basic core profiling algorithm is the same. Period.
I own my KPA since end 2012.
I chose an old IIC+ profile which was my favourite one in 2013, and downgraded to FW 1.8 IIRC. I played my main lead rig I used for my concerts. Everything was setup like in 2013.
I used DT-770 headphones.
Then I re-installed the FW 4.06 and played the exact same profile.
And then I understood a lot of things changed :
- low compensation stuff (my profile was made prior to this feature, so there was a small difference)
- cab hi and low features redesigned. I used a lot the low feature in 2013.
- Space parameter (I like it at about 5.0)
- Pure cab
- Hi and Low Shelf in the graphic eq I have in my X-Slot.
All of these features are not part of the profiling algorithm (except of the low compensation one for the very old profiles), but they make a hell of difference and I simply couldn't live without them today !!!
Of course I don't speak about harmonizer (transpose function for instance I use a lot to simulate a 7 string guitar) or stereo delays (yes I remember when we only had mono delay in the KPA)...
To me, the KPA has evolved significantly. Of course I would love few other features like the new delays, reverbs, and the double tracking effect, but TBH the KPA with his new features made me sell my real old Boogie amp. I wouldn't have sold it in 2013...