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abstract: 'The baseline energy-resolution performance for the current generation of large-mass, low-temperature calorimeters (utilizing TES and NTD sensor technologies) is $>2$ orders of magnitude worse than theoretical predictions. A detailed study of several calorimetric detectors suggests that a mismatch between the sensor and signal bandwidths is the primary reason for suppressed sensitivity. With this understanding, we propose a detector design in which a thin-film Au pad is directly deposited onto a massive absorber that is then thermally linked to a separately fabricated TES chip via an Au wirebond, providing large electron-phonon coupling (i.e. high signal bandwidth), ease of fabrication, and cosmogenic background suppression. Interestingly, this design strategy is fully compatible with the use of hygroscopic crystals (NaI) as absorbers. An 80-mm diameter Si light detector based upon these design principles, with potential use in both dark matter and neutrinoless double-beta decay, has an estimated baseline energy resolution of 0.35eV, 20$\times$ better than currently achievable. A 1.75kg ZnMoO$_{4}$ large-mass calorimeter would have a 3.5eV baseline resolution, 1000$\times$ better than currently achieved with NTDs with an estimated position dependence $\frac{\Delta E}{E}$ of 6$\times$10$^{-4}$, near or below the variations found in absorber thermalization in ZnMoO$_{4}$  and TeO$_{2}$. Such minimal position dependence is 