There is very, very, very little information online about the Korneff 45 amp. From what it looks like, these are not overly sensitive (a good thing), and should mate well with the low gain topology of the BeePre.
We considered the LDR option when developing the BeePre, but ended up going with a very high quality stepped attenuator. This doesn't mean that you can't use an LDR, just be sure that you get enough of them that you can get a tight match.