you could run an aftermarket DSP off the line-level outputs of the EONON + 2 amps, but seems a bit wasteful with the factory DSP sitting right there (and already calibrated). So I understand your dilemma. Perhaps use a small but high-quality pre-amp before the factory DSP that runs off the line-level outs?

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2001 X5 3.0i 5-speed manual (sport, tow, cold)
2018 Chevrolet Bolt EV
1981 VW Scirocco mid-engine VR6
1983 VW Vanagon Westfalia
2006 GSX-R750