I haven't heard the Threshold, but I did have a Krell KSA-50S and KRC-3 preamp for nine years.
One day I was in a stereo shop and noticed how much more real the cymbals sounded with a Musical Fidelity A308cr amp. I questioned the salesman about the difference and he told me that the KSA-50S was known to have a dark sound, and that was the difference I was hearing.
Chuck