Hi everybody, and first of all, thank you so much for all your help on this. I am so happy that kemper's community is so friendly and willing to help.
I have made more testings, following your advices, and I'm still having a latency around 889 samples (20ms) recording at 44.1khz with no rig, nothing in the stomps or effects, and something around 1170 with a basic preset with a rig, a chorus in the stomps and a delay and rever in the effects.
This is what I have done: (BTW, I made my testings with an old drum machine which has a clear sidestick to see the sound wave generated.)
1) Drum machine connected to my lehle split II
2) One Lehle's output to the analog front input of the KPA
3) The other Lehle's output directly to an API Preamp which output I have recorded in track 4.
4) Already inside the kemper, I am using the analog main outputs, and the direct output with then Git analog signal
So, I have been recording at the same time the following tracks
Track 1 - Analog Main Output Left from KPA
Track 2 - Analog Main Output Right from KPA
Track 3 - Direct Output from KPA
Track 4 - Direct signal from my drum machine coming from one of the two Lehle's outputs. In this track I have set a buss (pre-fader mode) with the SPDIF signal of the Kemper.
Track 5 - (Stereo track) - I take the signal of the bus inserted in track 4 and I recorded that.
The result has been that...
Tracks 3 & 4 are completely in sync as expected. I mean the direct output coming from KPA, and the direct signal coming from my Lehle are completely in sync. Well... I can see maybe a half of sample of difference in the waveform.
Between Tracks 1 & 2 (Main KPA outputs) and Track 5 (SPDIF output) there is a difference of 169 samples 3,8ms at 44,1khz.
Between Tracks 1 & 2 and Track 3 or 4 there is a latency of 889 samples (20 ms) at 44.1khz using No rig, nor nothing in the stomps of effects, and 1170 samples (26ms) at 44.1khz using the amp and a cabinet, as well as a chorus in the stomp and a delay an rever in the effect section.
Maybe I'm so sensitive to lag, hehe But honestly, playing some eighth notes with guitar mute in a funky song becomes very hard with this amount of latency. I'm sure you understand me.
Finally if all else fails and you’ve tried these suggestions and everyone else’ suggestions try a factory reset on the Kemper itself and failing that getting in touch with the support team. Your Kemper should add no more latency than any other digital guitar fx unit or stomp.
I will try to reset the unit and check if something changes as Per suggested here, and I will let you know if that made the trick. But I am not sure this is the problem here.
I will keep you posted!
Thanks again for your help on this.