@wlutke does 1 mm make a difference? You bet your socks it does. If IRC the alignment tool I use (an Acoustical Systems uniprotractor) assumes .1mm or less as the goal in setup (admittedly tricky to achieve in practice)
a read of the manual for this setup tool is quite illuminating for its discussion of the desired accuracy
a read of the manual for this setup tool is quite illuminating for its discussion of the desired accuracy