  In this short note we first extend the validity of the spectral radius
formula obtained in \cite{ag} to Fourier--Stieltjes algebras. The second part
is devoted to showing that for the measure algebra on any locally compact
non-discrete Abelian group there are no non-trivial constraints between three
quantities: the norm, the spectral radius and the supremum of the
Fourier--Stieltjes transform even if we restrict our attention to measures with
all convolution powers singular with respect to Haar measure.
