A aug7#9 — C6 Pedal Steel
A aug7#9 has no bar or slant position on the C6 Pedal Steel with the pedals up.
A aug7#9 stacks A – B# – C# – E# – G, and with every pedal up and every lever at rest no bar position on the C6 Pedal Steel sounds that set: at every fret, and on every short slant, a tone it needs is missing or too few strings carry it.
A pedal steel does not stop there. With Pedal 6 + Pedal 8 engaged, a straight bar at the nut spells it — 2 changes is the fewest it takes, and the copedent page lists every position, 5 in all.