So I was thinking about using the tools of functional analysis to study some subring of arithmetic functions under Dirichlet convolution. If I let $D_s$ be the ring of arithmetic functions with finite norm where
$$||f||_{s} =\sum_{n\geq 1} \dfrac{|f(n)|}{|n^s|},$$
then this should be a Banach Algebra. Now there is the Gelfand transform on this, for which I want to understand $\operatorname{Spec}(D_s)$. 

I can already tell you that there should be a copy of $\{t: \Re(t)\geq \Re(s)\}\cup \{\infty\}$ should be in the Spec. Why? The following are characters:
$$f\mapsto \sum_{n\geq 1} \dfrac{f(n)}{n^t} ,\quad f\mapsto f(1).$$

So my question is this: are these all the characters? Is the Gelfand transform useful in anyway to analyzing this ring?