This is exactly due to the dry/wet tuning, and less a matter of the box (AFAIK).
Pleasing harmonies occur when the frequencies of two notes have a nice
greatest common divisor (gcd). The best example is a note and the exact same note an octave above.
The frequency of the higher note is exactly twice the frequency of the lower note - which makes the frequency of the lower one the gcd. That's why two notes an octave apart sound so well together.
If we had two notes that had a ratio of two thirds or three quarters between them, they'd have very pleasing harmony as well.
Unfortunately our notes are just a tad bit offset from that due to
equal temperament.
That means that any two notes you'd pick (which aren't a whole number of octaves apart) have a nasty irrational ratio between them and they don't sound as good together as they would if you gave them a nudge to the right direction.
In comes wet tuning - instead of being exactly on point we have two notes that are slightly apart - this makes the note a bit "wider" so while it still doesn't fit exactly with other notes it does so less offensively to the ear and if you remember that all notes are "wider" they do manage to cooperate a bit instead of not at all.