Hello, Onhwy61 gives true advice, the closer they are to exactly imitating each other, the more exact everything is going to sound. I believe that after all else is said and done, many people neglect the last ounce of attention to detail with regard to exact speaker adjustments. yes, fore/aft & L/R are obviously key factors but getting the rake angle can also be very influential with most speakers and absolutely critical with others.Generally speaking, cone speakers are probably more forgiving but this angle can be the final factor when it comes to locking in imaging and improving location and placement of performers and their spatial characteristics.
Planar speakers are often much more dependent on rake angle being even and precise as it will truly snap the final focus into place. My planars are exactly rake adjusted [with plumb bob] to within 1/16th" as are the toe in measurements too.When they are out of adjustment I can tell...but [while keeping them basically level for the other placement adjustments],save rake as the last adjustment you make and you'll see ("hear') what I mean. Yes,it's worth the extra effort. Good luck.