Boss Tu15 used to be the most accurate tuner on the market back in a day when I bought it like 20 years ago, so I decided to check whether it's still in tune.
And after decades of use in the studio, at home, at countless rehearsals and gigs, it's spot on. Wow.
Why would I check? Because yesterday I desoldered it's annoying speaker that beeps if you're in tune every time you restart the unit and stumbled upon the calibration screw 😃.