Characterizing stage acoustics using objective parameters has seen some recent resurgence—several studies have noted the importance of the directionality of early stage reflections to musicians, which is not adequately represented using existing omnidirectional stage-support parameters. This study examines the subjective impressions of 19 chamber musicians against omnidirectional [reverberation time, early and late support (ST_Early, ST_Late), etc.], and proposed spatially-defined parameters (TH and TS), along with simple ratios of stage dimensions derived from measurements on eight purpose-built stages. TH is a ratio of early energy from "above" to that from the "horizontal," while TS relates energy from above to that from the "sides" of the stage. Robust mixed-effects analyses showed that the musicians' overall acoustic impression ratings are predicted (i) by TH within a linear model; (ii) by TH × ST_Early, TH × ST_Late, and TS × ST_Early, TS × ST_Late; (iii) by ST_Early, ST_Late each within parabolic models; and (iv) by several architectural parameters' linear and parabolic models. These findings reinforce recent studies of spatially-defined parameters to more fully account for the subtleties of onstage sound fields. Some simple design recommendations are presented, although future studies are needed to confirm these findings/recommendations for a wider range of auditorium stages.