Pressing both buttons on my unit cycles through filters. At each change the LED blinks. When it wraps around, it blinks twice. There are 5 filters in total. Below are their frequency and impulse responses. I named the filters f1, f2, ..., starting from the one with double blink.
Disclosure: the procedure (described below) may have some flaws I'm not aware of. The results look reasonable though, so there's that.
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For frequency response I used SoX to generate one minute of white noise at 44.1 kHz sampling rate, -10 dBFS sample peak (-5.3 dBTP, -14.9 RMS).
I played it at full volume and recorded with ADI-2 Pro RS R BE at 384 kHz sampling rate. Ref Level was set to +13 dBu.
For impulse response I used SoX to generate two seconds of silence with a one-sample impulse in the middle at 44.1 kHz sampling rate, -2 dBFS sample peak.
I recorded it like above and then added 4.4 dB gain (that's the difference between DAC's max output and +13 dBu Ref Level).