Vizio M21d-H8 vs LG SLM4R comparison definitely makes sense. Based on our rating, M21d-H8 has a total rating of 5 out of 10 versus 5.2 for SLM4R. The competitors' control buttons are different: power, volume down, volume up, source, Bluetooth and power, volume down, volume up, function, respectively.
Both soundbars have active amplification type. A significant difference between the units in the number of channels, the Vizio M21d-H8 has 2.1 versus 4.1 for the LG SLM4R. Only the Vizio M21d-H8 has a built-in subwoofer. The Vizio M21d-H8 got our rating of 5 out of 10, and the LG SLM4R 7 for its audio features and specs.
Soundbars do not have AirPlay support. Spotify support not implemented in both soundbars.
Both models do not have WI-FI support. Rivals from our review have Bluetooth support. Only the M21d-H8 supports HDMI Audio Return Channel (ARC). Both soundbars have a USB connector. For connectivity, each of the soundbars received a rating of 6/10. App control is available for the SLM4R. A built-in microphone is present only on the M21d-H8. Soundbars do not have Multi-room support.
None of soundbars equipped with Dolby Atmos multichannel audio decoder. The soundbars do not support the surround sound technology DTS:X. For multichannel surround, each of the opponents received 5 points out of 10.