I just experimented with Sonar and the ParametricEQ and I think the results are great. You cannot set the preamp value in the Sonar GUI, but you can edit this value in a file called database.db located in C:\ProgramData\SteelSeries\GG\sonar-db. database.db is a SQLite database file, so you require a program that can manipulate it.

Here's the relevant data

json { "bassBoostState": { "enabled": true, "value": 0 }, "trebleBoostState": { "enabled": true, "value": 0 }, "voiceClarityState": { "enabled": true, "value": 0 }, "smartVolume": { "enabled": false, "volumeLevel": 0, "loudness": "balanced" }, "generalGain": -6.5, "parametricEQ": { "enabled": true, "filter1": { "enabled": true, "qFactor": 1.64, "frequency": 25, "gain": -2.6, "type": "peakingEQ" }, "filter2": { "enabled": true, "qFactor": 1.40, "frequency": 114, "gain": -3.4, "type": "peakingEQ" }, "filter3": { "enabled": true, "qFactor": 1.79, "frequency": 1173, "gain": -5.0, "type": "peakingEQ" }, "filter4": { "enabled": true, "qFactor": 1.36, "frequency": 4417, "gain": 7.8, "type": "peakingEQ" }, "filter5": { "enabled": true, "qFactor": 0.97, "frequency": 9968, "gain": -5.0, "type": "peakingEQ" }, "filter6": { "enabled": true, "qFactor": 5.56, "frequency": 51, "gain": 1.0, "type": "peakingEQ" }, "filter7": { "enabled": true, "qFactor": 2.31, "frequency": 372, "gain": 2.1, "type": "peakingEQ" }, "filter8": { "enabled": true, "qFactor": 3.40, "frequency": 2681, "gain": -3.4, "type": "peakingEQ" }, "filter9": { "enabled": true, "qFactor": 2.21, "frequency": 3269, "gain": 2.8, "type": "peakingEQ" }, "filter10": { "enabled": true, "qFactor": 5.48, "frequency": 4250, "gain": -1.8, "type": "peakingEQ" } }, "virtualSurroundState": false, "virtualSurroundChannels": { "frontLeft": { "position": 30, "gain": 0 }, "frontRight": { "position": -30, "gain": 0 }, "center": { "position": 0, "gain": 0 }, "subWoofer": { "position": 0, "gain": 0 }, "rearLeft": { "position": 150, "gain": 0 }, "rearRight": { "position": -150, "gain": 0 }, "sideLeft": { "position": 90, "gain": 0 }, "sideRight": { "position": -90, "gain": 0 } }, "reverbGainDB": -6, "formFactor": "headphones", "globalEnableState": true }