Generally users would use a computer with HTPC only if there is another reason to have a PC connected to the TV (such as a gaming PC) or if the increase in quality is worth the cost for them.
That aside I answered some hardware recommendations here: NUC or equivalent choice for 4K movies without any transcoding (Atmos / DTS / DolbyVision / IMAX ) - #6 by gbooker02
Per streaming boxes, if you want HD audio codecs, I’d avoid the AppleTV. I believe it is still lacking HD audio codec passthrough. I believe the FireTV is the same.
The Shield can passthough HD audio.
