CMA6 4 STRING GROUPS NO OPEN STRINGS E-D-G-B [E] [A] [D] [G] [B] [E] * * * * C * *# * E A *# *# G * * * D * *# *# *# * *# *# A * G C E * * * * * * * * * A * *# * C * * * G * *# *# * E *# *# * * C * A * *# *# *# *# *# *# E * * G * * D-G-B-E [E] [A] [D] [G] [B] [E] * * * * C * *# * E A *# *# * * * * * G *# *# *# * *# *# * * G C E A * * * * * * * * A * *# * * * * * G C *# *# * E *# *# * * C * A * *# *# *# *# *# *# * * * G * E A-D-G-B [E] [A] [D] [G] [B] [E] * * * * * * *# * * A *# *# * C * * * * *# *# *# * *# *# * * G C E * * * * * * * * E A * *# * * * * * G * *# *# * E *# *# * G C * A * *# *# *# *# *# *# * * * * * * E-A-D-G [E] [A] [D] [G] [B] [E] * * * * * * *# * E A *# *# G C * * * * *# *# *# * *# *# A * G C * * * * * * * * * E A * *# * C * * * * * *# *# * E *# *# * G * * * * *# *# *# *# *# *# * * * * * * A-G-B-E [E] [A] [D] [G] [B] [E] * * * * * * *# * * A *# *# * C * * * G *# *# *# * *# *# * * * C E A * * * * * * * E * * *# * * * * * G C *# *# * E *# *# * G * * A * *# *# *# *# *# *# * * * * * * It's worth noticing that all that has happened is we have taken the B, which is the major 7 interval, and lowered it two frets to A, which is the sixth interval. I‘ve seen this also analyzed as a Maj 13, but I think that‘s artificial. There‘s only a Cmaj triad and an A. Much more important is to notice that this also spells an Ami7 Chord: A-C-G-E, when we analyze A, the sixth of C as the Root. By extension this spelling is also synonymous with Fmaj without a root. (F)-A-C-E-G. If you go back to the Cmaj9 forms, you will see that they also can be viewed as synonymous with both Emi7 and G6. As in language, the taste of the composer/stylist will dictate their applications in context. Some things will simply sound better than others in the course of applying these voicings to specific progressions and larger arranging contexts.