I just upgraded my late 2017 MacBook Pro 13'' to a new M1 MacBook Air (both with 8GB/256GB). I don't have the old Intel one any more, but at first listen the new M1 sounds even better. Very "quiet", if that makes any sense.
Probably expectation bias, but overall I'm very happy with the SQ of 1.5.
On a different note, I'm just somewhat puzzled by the rapid inflation of the Studio version numbers. We're already at 1.5 with barely any visible changes, in just a couple of weeks. Remember the HUGE differences between A+ 1.x, 2.x and 3.5? At this speed we get there before y