Brain Game: By the Neck

A certain group of readers will have no problem with today's Brain Game; and I'm sure they'll make themselves known. For the rest of you, good luck:

What's the last letter in this sequence? E, A, D, G, B, ?

Here is the SOLUTION.

THE SOLUTION:

E.

The letters represent the tuning of the strings on a typical six-string guitar. Both the top and bottom strings are tuned to E.