Does the Devore Fidelity Orangutan 0/96 speaker play rich and full bodied at 50 Decibels

Agree with others - 50 dB seems pretty low.

For low-level listening I always thought that crossover-less, single-driver speakers (perhaps from Omega Speaker Systems) and a SET or small push/pull amp would be ideal. You’d have point-source imaging while bypassing a resistive crossover - and if needing to further address the Fletcher Munson Curve you could throw in a transparent two-slope equalizer in the path like the ZRock from Decware. 

Whether technically right or wrong, this is essentially what I did for a period of time that yielded good results.

If I had to choose, I’d spring for those O/96’s any day of the week while pushing up the SPL - endgame speakers in my book. 

I’ve heard the Devores and they are very beautiful sounding. Delicate and rich and ‘real.’ Similar quality to Audio Note speakers, which also sound excellent at low volumes. I do not think you’d be disappointed with Devores or Audio Note AN-E’s, which I currently own. But, if you wanted such low volume, would near field listening be a better option? You could go with Falcon Ls3/5a’s or Audio Note AN-Ks with a low powered tube amp.

Or headphones

I have not heard a direct comparison of the Volti Lucera and Devore O/96, but I have heard both and they are both good at lower volume levels.  So are other speakers mentioned here and in your other thread, like Charney Audio speakers, Audio Note speakers, and the Quad 57 (original quads).  I would not make a choice based on assumptions about particular design considerations.  I disagree with any generalization that large woofers cannot play well at low volume levels; I’ve heard many a horn system that were particularly good at lower volume levels levels including systems with 18”, 22”, and 31.5” woofers.

Get a Schiit EQ. If I need some fidelity at low levels (rare...if it's low I'm not seriously listening) a Loki Max with remote is great.