Given that $\displaystyle \int _{ a }^{ \infty }{ \frac { { e }^{ x } }{ { 9e }^{ 2x }+64 } dx=\frac { \pi }{ K } }$, where $a=\ln { \left(\frac { 8\sqrt { 3 } }{ 3 } \right) }$, what is the value of $K$?

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