Thanks Lights, now we can see better what´s going on:
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As you can see; there´s an increased decay time at 40 Hz using the ARC2 (and it´s not fan rattling you see in the measurements). Please note that I´m not saying that the overall situation is better without the ARC2, I´m just trying to show that these systems cannot replace proper acoustic treatment (and I´m not suggesting that you believe so, but there are many out there who do). It might be a last option once treatment is competed or the last resort if no treatment can be added to the room for various reasons.
If you make new measurements; don´t limit the frequency range to 400 Hz. Make it 20 (or even 10) Hz to 20 kHz sweeps (and use 512k sweep length). You can improve your S/N-ratio by doing multiple sweeps (averaging). Also; play the speaker fairly loud. Just below to the point they start to change character or distort audibly.