Hendrix' Star Spangled Banner is not in any sense a sign. The audience at Woodstock had attended to see Hendrix perform, not to experience a communal National identity.
Hendrix' performance is not the Sign, it is the Signed.
If you want to use this piece to discuss simulacra, you need first to recognise that the Hendrix performance is the object, while the ideal (and largely notional) [American National Anthem] is -in this instance - the simulacrum.
Hendrix' performance was authentic, and an enactment of the expectation of the paying crowd. It is the (factitious) [American National Anthem] which is the simulacrum (inasmuch as the reduction of the authentic performance to a specie of an imaginary National Symbol was performed exclusively by people who had not been present at the authentic performance, and neither could - nor wished to - understand it.
Hendrix' performance in fact created the [American National Anthem] as a fourth order (null set) simulacrum. People who had not been present at the authentic performance referred the performance to an unheard, and unhearable 'authentic' performance of [The American National Anthem] as a method to denature and avoid the authenticity of the original. The [American National Anthem] was erected as an unhearable, unplayable 'authentic' performance, against which the actual authentic performance was measured and condemned.
But an unhearable, unplayable performance is no performance at all;- it is merely a stratagem for avoiding authenticity.
A stratagem for avoiding authenticity is at least a fourth order simulacrum; maybe higher.