Let $\delta {\mathcal{E}}_p$, $p>0$, be the real vector space containing functions of the form $u_1-u_2$, where $u_1$ and $u_2$ are non-positive plurisubharmonic functions with finite pluricomplex $p$-energy. We prove a convergence theorem and give an example of interesting continuous mappings on this quasi-Banach space.