ART Pro Audio Dual Tube EQ - Two Channel, Tube EQ - Manual (Page 14)

should give you a good place to start.
APPLICATIONS
The Tube EQ is intended for use with line level sources. The
proper placement of the Dual Tube EQ in a signal chain is: after
a mic/line preamplifier, after a direct output or bus output from a
console, after the output of a tape deck, or in the insert point of
a mixer.
The Dual Tube EQ has gain and it is possible to plug an instru-
ment directly into it. However, the Dual Tube EQ does not have
enough gain to properly preamplify a microphone plugged
directly into it.
1 13 3
~ In the Channel Insert of a Mixer ~
~ Direct to Tape through Pro MPA, Pro VLA and Dual Tube EQ ~
CHANNEL INSERT SEND
CHANNEL INSERT RETURN