  The super-Macdonald polynomials, introduced by Sergeev and Veselov,
generalise the Macdonald polynomials to (arbitrary numbers of) two kinds of
variables, and they are eigenfunctions of the deformed Macdonald-Ruijsenaars
operators introduced by the same authors. We introduce a Hermitian form on the
algebra spanned by the super-Macdonald polynomials, prove their orthogonality,
compute their (quadratic) norms explicitly, and establish a corresponding
Hilbert space interpretation of the super-Macdonald polynomials and deformed
Macdonald-Ruijsenaars operators. This allows for a quantum mechanical
interpretation of the models defined by the deformed Macdonald-Ruijsenaars
operators. Motivated by recent results in the nonrelativistic ($q\to 1$) case,
we propose that these models describe the particles and anti-particles of an
underlying relativistic quantum field theory, thus providing a natural
generalisation of the trigonometric Ruijsenaars model.
