I'm not 100% percent sure, but sample rate and clock go hand in hand. So a sample rate of 48 kHz means a clock of 48 kHz. The Kemper can't be a slave, so it has to generate the clock itself.
I hear you. It seems quite strange tho that the manual only mentions the clock and disregards sampling frequency, which would seem much more relevant.
Maybe someone from Kemper might shed a light on this? timo?