I was gung-f'n-ho on the Sprout when the original Kickstarter launched: the concept, the marketing, the appearance, the feature set - everything.
But while I was saving up for one, Stereophile published those jaw-dropping measurements showing a 7 db 70 Hz boost and steep 50 Hz highpass. While I acknowledge that this may compliment some small speakers, the design choice makes Sprout useless to me. Sprout II evidently continues with this bold "voicing".
To disable/enable, one must press and hold the push-button volume knob (knob on the left). The indicator light will blink and then the light will turn blue instead of white, which is your indication that the amplifier is now in no-filter mode. Hope that helps!
In even more ways than before, Sprout begs comparison with the TEAC AI-301DA. Same B&O amp module now, similar feature set. Sprout100 has onboard phono and pre-outs. AI-301DA has additional line and digital coaxial inputs, and can be had ~$300 cheaper.