Phoenix Audio DRS-1R - Mono Class A Microphone Pre-Amplifier/DI in API 500 Series - Manual (Page 3)

NOTE: The MIC/Line input selection push-button stays illuminated until the
input source is changed to the 1/4” jack socket by pressing the DI button.
DRS-1R SETUP INSTRUCTIONS
The DRS-1R has a vertical row of LED’s to indicate level. These LED’s are
connected to the OUTPUT of the unit, NOT the mic-pre section. This
makes the LED’s indication much more useful for setting up levels on
the Mic-Pre and the DI, and to give you a clear view of what level is being
sent to external equipment.
The LED’s are marked –2,+4 and +10 (Green) and +13 (Yellow) and
+18 (Red). When the Red Led lights, this isn’t a sign of clipping as the
Pre-amp will have at least another 8db of headroom.
The Mic Sensitivity Knob and the OUTPUT level knob work independently
of each other. The Mic Sensitivity knob has no effect on the DI input.