There are any number of reasons for your mixes to sound harsh, they range from overdriving the preamps in the Mackie to bad microphones or bad placements on the instruments to peaking the mixing bus with too many hot signals and then turning down the master fader to compensate. You could also have blown speakers or blown headphones that are sounding harsh because they are ripped or torn, Best suggestion is to record something like an acoustic guitar and normal levels with at least two microphones, mix it down watching your headroom on the master fader and listen to it and see if it sounds "harsh' Then start working bakewards and eliminate each item from the speakers backwards,

If you suspect the microphone subsitute a known good one the same with the speakers and headphones. Just because the console is in 32 bit float does not mean that the the console could not be at fault and you may have a bad mic pre or the console itself could be having problems (power supply, solder connections, component shift)

Lots of variables so you have to take the time to find out exactly where the signal is sounding "harsh"

Best of luck

WHERE it starts to sound harsh is the key... Is it harsh at the track level? Mix level? Post?

Hello, i was monitoring level quite precisely and left 24dBm headrom.

Maybe word harsh is not very good, but my mix&master sounds like: German Mixes of "JULI - perfekte welle" or other her songs.
But never sound like "Janette - Hold the line",
it has warm sounding with lot of ambience, the question is WHY?
How to acheve this?
Maybe K-System Processor for ambience, i don't know about it, and have not listened.