Krell Industries Digital to Analog Processor STUDIO 2 Owner's Reference Manual page 12

OPERATION
0 ° and 180 ° PHASE SWITCHING
The absolute output phase of the STUDIO 2 can be changed. In
some recordings the master tape was recorded out of phase,
creating unusually poor sounding recordings. The STUDIO 2 can
shift the absolute
output phase 180 ° to correct
for this anomaly.
To change the phase from 0 ° to 180 °, press
the 180 DEG button.
To change back to normal phase, press the 0 DEG button.
Utilizing the Phase Switching can, in some instances, restore life
to a previously dull sounding recording.
EMPHASIS LED
Emphasis is a recording technique that accentuates the treble
region of recorded music. Discs and/or Tracks that were recorded
with Pre-emphasis will cause the Emphasis LED to illuminate.
When the Emphasis LED is lit, the appropriate complementary
circuitry (De-emphasis) is activated to provide a fiat output
response.
PAGE 12