Bartok as a preamplifier

I found in the data sheet of Bartok that the recommended input impedance is 10k-100kΩ

1 x pair balanced outputs on 2 x XLR connectors. Output levels: 0.2V, 0.6V, 2V, 6V rms for a full-scale input, set in the menu. Output impedance: 3Ω Maximum load: 600Ω (10k-100kΩ is recommended)

Next, I look at the input impedance of my ATC SCA2 preamp and see that for a balanced input it is only 2k7 per leg.
At the RCA input, everything is pretty standard.

What does the recommended 10k-100kΩ mean and how can this affect the sound in the case of working with a preamp where the input impedance is 2k7?

image