OS 1.5.0 was one of the OS having so called "aliasing " .
Anyway, it was very good sound of KPA, actually the best one sound of KPA.
Than, in 1.6.0 they get rid of aliasing , causing the biggest debate over Kemper forum up to date.
Say , about half of users thought 1.6.0 destroyed natural organic KPA sound ,where another half said no change in KPA tone after and before removing aliasing .
Today , I played TAF Fargain The King (retro ) via OS 2.1.0 and via OS 1.5.0
After 5 seconds of playing it with old, 1.5.0 OS , I realize what is the Kemper KPA : the best guitar device of 21st Century .
Also, I realise , that KPA with 2.1.0 is still the good , but not the best , something was missing , and that was not missing with 1.5.0 .
I don't have fancy equipment of re-amping etc...but , if my self , 4 members of my family , 3 neighbours and two dogs clearly prefer natural, deep, wide, organic, warm, brownish sound of 1.5.0 over sound of 2.1. 0 - what I have to do ?
...I have to stay with 1.5.0 and wait , and this is exactly what I am going to do .
I do not want to start the same discussion again, I just want to let you know that you have a choice to go back to 1.5.0 wait.......CK will do that one day , I am sure- some future X.Y.Z OS will have that natural sound of 1.5.0 .
Also, this is just my subjective ,personal view , which might be completely wrong for anyone else view , and it is not based on any scientific measurement, just on subjective feeling, which might be badly wrong, again.