Krell KRC preamp question?

The Krell KRC-HR and KRC can't sound different because they are identical piece
HR is only to be able to connect your theater-throughput thru the input S4
if you don't use your A/V surround system you will no need that feature

Here is a copy from the manual about the only difference

THEATER THROUGHPUT
The $4 input of the KRC-HR can be set to operate as a unity gain stage. This
removes the KRC-HR volume control from the signal path. Volume control is
then transferred from the KRC-HR to an A/V surround processor connected to
the $4 input. This feature greatly simplifies the installation of a surroundsound
processor into a high performance audio/video surround system.
If the Theater-Throughput option is activated, select S-4 when your home
theater/surround system will be used. In this mode, all control of volume is
performed by the A/V surround processor connected to that input. Specifically,
Level, Balance and Gain are disabled on the KRC-HR for the S-4 input only
when the Theater-Throughput is engaged. Mute and Tape (monitor input) will
function normally.
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