Can I use the EQ separate from the preamp on the 583e?

YES! This was the intention. Think of the EQ section on the 583E as its own module that can be used as if it weren’t part of the 583 preamp or, as a simple pre+EQ channel strip. Running the EQ separately is accomplished simply by flipping the toggle switch on the lower right to “Pre/EQ”. In this mode, the 583E is now two completely separate units. The EQ path is re-routed to the corresponding XLR input/output jacks on the power supply and can be used however the user wishes. When the same toggle is flipped to “Pre+EQ” the EQ path is patched to serve the preamp. Below are a few ways to apply these functions.

Scenario 1: The 583E is being used to record acoustic guitar but, you realize you need an EQ on a different preamp that’s being used for the vocal track. In this case, flip the EQ toggle to “Pre/EQ”. In this mode, you can still use the 583 preamp on acoustic guitar but the EQ section is now available to be routed to the vocal preamp.

Scenario 2: You’ve finished recording and are preparing to mix. You’re set with in-the-box EQ’s but need something more natural sounding to shape/sculpt the electric guitar track. With the 583E switched to “Pre/EQ” you can patch into the EQ section’s XLR input/output jacks for this task.
Scenario 3: You’re using the 583E to amplify the microphone used to record a violin. You love the mic/preamp combo but would like to nudge a little more low-mids before recording. Flipping the EQ toggle to “Pre+EQ” auto patches the EQ to serve the preamp in this way. In this mode the 583E is functioning as a channel strip.