What voltage is the 3.5mm audio jack on I/O board? (re: connecting to amplifier, volume is too loud)

[sofakng]

I'm using the MiSTer in a custom arcade cabinet and I'm having an issue where the volume is extremely too loud.

The MiSTer connects from the 3.5mm jack on the I/O board to an amplifier. The amplifier has the following different inputs:

* Pre-amp Line Level Input Connector (2x RCA)
* Floating Ground Speaker Input (4x pins; Molex-style connector)

The amplifier also have a sensitivity adjustment from 250mV to 4V. However, even at the minimum (250mV or 4V? I forgot which reduces the volume?), the volume from the MiSTer is still extremely too loud even with the MiSTer volume (from the menu) at the bare minimum.

Can anybody help me or explain what I might need to do?

Is the 3.5mm audio output from the I/O board considered "line level" ? I see the schematic lists a 560 ohm (?) resistor but I'm not sure what that means regarding the audio output.

[LamerDeluxe]

I've used the audio output before, connected to a headphone amplifier and connected to a SCART cable and had no volume issues.

[ash2fpga]

I do not have a direct answer. I checked several audio threads on the AT forum, but did not find anything specific about line levels.

I have used the analog audio from the 6.1 board through an OSSC, and the speakers on a NEC 20WMGX2 monitor and had no issues. I briefly checked for OSSC audio input specs, but did not immediately find any. I did find specs for the monitor audio input: RCA PIN-JACK L/R 1 INPUT, STEREO Mini Jack 1INPUT 500mV rms Input Impedance 22 Kohm

Not sure if any of that helps, though.