Update on two-level sampling for glueball observables in quenched QCD

We report our progress in combining a two-level sampling algorithm with distillation techniques for calculations of disconnected diagrams in quenched QCD. The simulations are performed on a single ensemble at $\beta =6.0$ and volume $V={16}^3\times 64$, and at a pion mass of $m_{\pi }\approx 760\mathrm{M}\mathrm{e}\mathrm{V}$.