What is the input impedance of the Classe DR-9 amp

The crossovers on my new Vandersteen Quatros have to be set up to match the driving amp's input impedance. Unfortunately, the owner's manual that came with my Classe DR-9 doesn't give the input impedance. Does anyone know the value?
I believe it is 100K ohms.I had these in a bi-amp situation with various crossovers.
According to information I found on the Internet, the input impedance is 53,000 ohms.
Why not try the obvious? Get in touch with the mfg.
The Model 15, similiar to the DR-9 is 70K into the RCA inputs. The balanced input is probably 1/2, not double as you would expect. This due to the fact that the circuit is not true differential. Either way, any pre-amp will drive it to full output no problem.
Thanks for the input. Tech support at Classe couldn't tell me for sure, saying they thought it probably was 50-100K, similar to the responses here. I might have to resort to finding an oscilloscope and 'tuning' the crossover based on how the amp responds to input waveforms.
The input impedance that I supplied was for the RCA/unbalanced inputs.
According to a review in Stereophile vol 11 no 10 by Arnis Balgalvis, input impedance in stereo mode was 100k and in bridged mono 25k.