saith the Ferenghi.
I comprehend the numbers you're mentioning.. somewhat.
Putting on audio-conslutant hat, from days of yore when early Ge(rmanium) transistor kluges were attempting to match the best vacuum tube techno of the day: I applaud your efforts to rescue say, serious wide-range audio form the horror that is the mp3 spec (and now, almost the Only) widely circulated format :-/.
That is, merely (!?) matching the dynamic range of the (best-of the) vinyl LPs, re. full orchestra (or throw in a chorus, a pipe-organ, triangles --> string or brass bass -- too): needs likely even higher switching-freq than your current level. But at least, your recipe sounds as if it would be listenable playback [of said material] to a crank like moi. And that S/N ratio is equally admirable.. one Wants an 80dB dynamic range, where possible.
(This-all, of course, is why I'd need to do heroic techno things even to create a portable 'player') in no way connected to iTunes libs, etc. -- capable of replaying high quality material with the distortion, dynamic range specs of a '60s Uher Report-L 5"-reel portable player ... the size of a couple cigar boxes. I peddled my last one on ePay some years back. Alas, they were pretty heavy, with cast alloy cases and gel-cell or 5 D-size nicads. They could be got with 4-T or 2-T config. I recorded 2-T a piano soloist from audience, SF Symphony.. with his permission but not with Union-OK: ergo, mic in each hand, wires down sleeves, Uher under a 'coat'. Result was bitchin, played back on a Crown CX-822 into Marantz + KLH-Nines full-range electrostatic speakers. Etc.
This was the poor-man's Nagra, except that Uher specs were much better re flutter/wow and, IIRC distortion at -3 dB VU level. It used a quite sophisticated closed-loop DC-motor control + heavy capstan to achieve those specs.
Mixing and audio/video rendering -in-sync- aside; a vast complexity as you have described:
are you aware of any small 'digital' record/playback devices extant, that are rather small, aka equalling the best of analog 'Walkman-type' players of yesteryear? if not quite so small.
(I have too many Other-irons in fire to scheme to cobble up some kluge, likely via components not necessarily designed to play well together.)
Thanx for any tips
I, audiophile..
Music! an absolutely indispensable antidote, emollient to the cacophony of the Age, especially the biped-mouthnoise sort.