Steely Dan and the μ chord

Those crazy jazz-rock dudes loved add2 chords so much they adopted the Greek letter mu as a moniker!

But they also taught us two other crucial things about that chord; 

1. That it sounds best in first inversion

2. That it must be used sparingly

Above you can see one of a thousand uses, this time judiciously placed in the chorus of Fagen's 'Morph the Cat'. 

Triad + Triad = Hexatonic

Say you're blowing on a 7#9 bluesy vibe, C7#9, let's say.

We know that the dominant diminished thing is cool, but it can sound a bit synthetic.

So there's a handy way of reconnecting with the blues, combining triads to make a cool melodic shape.

Kenny Kirkland on 7sus chords

In this phrase the late, great Kenny Kirkland nods to both Herbie and McCoy. The pentatonic construction is straight out of McCoy's bag whereas the note choices employ a technique often used by H.H. - using the major third over a 7sus chord gives a super rich colour to the melody. 

This works so well because the 3rd (usually a pretty ordinary note) becomes a tension due to it being replaced in the lower chord by the 4th, it's muscular next door neighbour.  

A quick trick is to play the pentatonic scale on the same root as the 7sus chord.  

Here's the track (phrase at 1:32)  

RIP Kenny Kirkland, you did so much for jazz piano.