[en] High-precision jet spectroscopy will be increasingly important in future high-energy accelerator experiments, particularly at a linear e⁺e^- collider. The dual-readout technique makes it possible to meet and exceed the requirements on calorimeter performance in experiments at such a collider. The DREAM Collaboration is exploring the limits of the possibilities offered by this technique, by systematically eliminating the limiting factors, one after the other. Powerful tools in this context are the simultaneous measurement of scintillation light and Cherenkov light generated in the shower development process, and a detailed measurement of the time structure of the signals. In this talk, the latest results of this generic detector R and D project are presented. In particular, I report on the first tests of a hybrid dual-readout calorimeter system, in which a BGO crystal matrix served as the electromagnetic section.