If the frequency range of the 6381 extends above, say 200hz, it 'could' effect the soundstage, however most of the soundstaging issues are dependant on good mid-range and high frequency reproduction as heard in the sweet spot. Its the high frequency overtones that really are most important, both positively and negatively (in the case of 1st reflections).
What might occur when you block the path of the low frequencies is you could change the tonal response of the speaker's bass response a tad. I'd be more concerned with the possible differences with the overall tonal response in your room between the two speakers than I would be concerned about soundstaging issues. JMHO YMMV.
What might occur when you block the path of the low frequencies is you could change the tonal response of the speaker's bass response a tad. I'd be more concerned with the possible differences with the overall tonal response in your room between the two speakers than I would be concerned about soundstaging issues. JMHO YMMV.