Phoenix Audio DRS-EQ/500 - Mono Class A 4 Band EQ for the API 500 Series - Manual (Page 3)

.
DRS-EQ/500 SETUP INSTRUCTIONS
The DRS-EQ/500 has a vertical row of LED’s to indicate level. These LED’s
are connected to the OUTPUT of the unit, NOT the input section. This
makes the LED’s indication much more useful for setting up levels on
the EQ, 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
EQ will have at least another 10db of headroom.
You can turn the output knob all the way up to maximum and still be sure the
output of the unit will not clip. The amount of headroom on both the input
AND output stage is HUGE!!! There will never be a time when you can't get
a hot enough output, only occasionally too hot an input (then you just simply
turn down the input signal coming into your EQ.
The OUTPUT level knob is provided to allow OUTPUT level adjustment.
If you prefer to have a “hotter” output, turn the OUTPUT knob up to suit.
You can turn the OUTPUT knob fully up without any distortion as there is
plenty of headroom on the output stage. Also, if you prefer to have a LOWER
level on the output (I.E.: for semi-pro outboard gear which requires around -
10dB input), simply turn the OUTPUT knob down to taste. The combination of
the Class A discrete output stage coupled with our custom
wound transformer will impart second harmonics into your music
and also a form of compression, similar to tape compression, this will be
achieved by running the unit with a high output level.