The Modwright is a state of the art linestage. I haven't heard the Krell but I can't imagine any pre/pro coming close in sound to the SWL 9.0SE.
There are no SSPs made that can compare to even an average
2 channel preamp. The 9.0SE Is one of the best 2 channel
preamps I have heard and currently own.
The HT bypass allows for your surround processor to be ran
through the 9.0SE for your front left and right speakers.
Your surround processors inputs would be used for the center and surrounds only. This allows you to have both a great
Ht setup and great 2 channel sound in one system.
Hope this helps and good luck.