Tested along my personal quest for a buffer that doesn't alterate the sound of my passive Drop A guitar, meaning high input impedance not to load the pickups and flat frequency response all along the spectrum, even towards low frequencies. Because low end buffers were not satisfying I added this preamp in my last testing batch to see If it could do the job. So it is definitely not done for low tuning instruments with a cutoff at -3dB at ~55Hz, but rather "flat" from 90Hz (+/-0.5dB let's say). I would have liked a notch for the neutral position on the knobs. I think the possibility to hold it on the belt is a really nice feature that doesn't seem to be widespread...