A quick dip in the GooglePond revealed that Fire Stick plus streaming video movies plus HDMI-based sound equipment doesn't always result in Dolby 5.1 sound, without a deep dive into settings, sources, and interconnect methods. Way, way too many variables to attack here. Without being 'set up' correctly to do 5.1, a sound bar won't really sing. They're not 'all that' to begin with, but they usually perform better than a basic stereo TV with 3" speakers in-cabinet.
I have a Vizio 4k that's a year or two old, and a Vizio sound bar connected by either HDMI or optical (don't recall) and it is a step or two up from the TV's speakers. Good WAF, also, from a operational and decor standpoint.
In a former life, I was an actual recording engineer. While I have good stuff in other areas, I quickly realized there was no point in chasing real studio quality with consumer stuff. The cost in square footage, dollars, complexity, etc. wasn't worth it when you took into account the acoustical environment you were in -- a standard living room, with external noise sources and normal surface finishes. If a listening session mattered enough, I just went to the studio instead. Nowdays, it's easier to get 'good', but 'pretty much perfect' is elusive.