Vizio M Series M51ax-J6 Soundbar Review

The Vizio M51ax-J6 is a soundbar with a simple, sleek design. The bar is mostly made of plastic, and there's a thin fabric covering the front and the sides.

The sub sits on four plastic pegs with rubber grips. It's mostly made of melamine, and the port is located in the rear. The speaker is located underneath.

The satellites have a similar design to the bar. They're mostly plastic, with a thin fabric covering the front and the sides. They need to be wired to the sub to function. If you don't have room in your setup for satellites, you can always check out an option that comes without them, like the Vizio M Series M215a-J6.

The Vizio M51ax-J6 isn't very wide, but it may not fit between the legs of a 55" TV stand. That said, it also isn't very tall, so it shouldn't obscure your TV screen unless your TV sits flush on the table.

The sub is roughly the same size as that of the Vizio M Series M51a-H6. It's a bit shorter than the average desktop PC.

The satellites are fairly small. You only need to plug them into the sub to get them to work, so you have some flexibility when placing them in your setup.

The Vizio M51ax-J6 has a decent build quality. It has a very similar look and feel to the Vizio M Series M51a-H6. The bar and the satellites are mostly made of matte-textured plastic, which feels solid and durable overall. However, the fabric coverings on the front and sides seem like they could rip or collect dust easily. The sub is mostly made of melamine, which feels solid. For a better built soundbar, check out the Samsung HW-Q59CT.

• Manuals
• Mounting template
• 4x wall mount brackets
• 4x wall mount screws
• Remote with batteries (2x AAA)
• 2x power cable (8.5 ft / 2.6m and 4.9 ft / 1.5m)
• 2x surround speaker audio cable (26 ft / 8.0m)
• Optical cable (4.9 / 1.5m)
• HDMI cable (6.2 ft / 1.9m)
• 4x cable ties

The Vizio M51ax-J6 has a great stereo frequency response. With its 'Direct' preset, it has a very neutral, balanced sound profile that's suitable for listening to lots of different types of audio content. While we noticed some port noises and rumbling in the low-bass, this may be unique to our testing unit. You can also customize its sound using the EQ presets as well as the bass and treble adjustments.

The Vizio M51ax-J6 comes with bass and treble adjustments, as well as EQ presets to help you customize its sound profile to your liking. While we tested the bar in several configurations, we found that its default sound profile offers the most neutral response.

The Vizio M51ax-J6 has a decent stereo soundstage performance. The soundstage is perceived to be a little bit wider than the bar itself, but it doesn't have any tricks to make it seem wider than that. It has good focus, though, so objects in the soundstage like voices seem to come from a pinpoint location rather than a general area. For a better stereo soundstage performance, check out the Vizio M Series M512a-H6.

The Vizio M51ax-J6 has a great stereo dynamics performance. This soundbar gets pretty loud, and there isn't much compression when you push it to max volume. You can crank up the volume to fill up large spaces and crowded parties, and audio reproduction remains mostly clean.

The Vizio M51ax-J6's stereo THD performance is good. At normal listening volumes, it falls within good limits, resulting in clean and pure audio reproduction. However, there's a jump in THD when you push the bar to max volume. That said, THD can be hard to hear with real-life content, so you may not notice it.

The Vizio M51ax-J6 has an excellent center channel performance. This 5.1 setup has a discrete center channel that helps accurately localize voices to a pinpoint location in the sound image. It also has a neutral frequency response, especially in the mid-range where dialogue reproduces, so voices are clear and detailed.

The Vizio M51ax-J6 has a satisfactory surrounds performance. Thanks to its discrete surround speakers, surround objects like voices are clearly and accurately represented in the soundstage. Its frequency response is slightly bass-heavy, so audio content has extra thump and punch.

The Vizio M51ax-J6 has a middling Atmos performance. It uses front-firing speakers on its satellites to bounce sound off the ceiling and back down towards you to create the illusion of height. It performs better than similar 5.1.2 setups like the onn. 42" 5.1. 2. Dolby Atmos Soundbar. However, this doesn't sound as real as discrete down-firing speakers in a home theater setup.

The Vizio M51ax-J6 has a decent selection of sound enhancement features. There are some EQ presets so you can customize its sound, including 'Direct', 'Movie', 'Music', and 'Game'. You can use the dialogue enhancement feature to make voices more clear and crisp, and use the TruVolume feature to provide a consistent volume level across programs. However, it lacks more premium features like a graphic EQ or room correction, so it may sound a bit different depending on the room you're listening in.

The Vizio M51ax-J6 has several inputs. There's a Full HDMI In port, so you can use it as a hub between different devices. You can also use the AUX In port to connect older devices for audio playback.

Update 10/20/2021: We received feedback from a user who experienced issues playing LPCM content over Apple TV and Xbox. However, we weren't able to replicate this phenomenon in our tests. We confirmed that the bar can playback 5.1 PCM.

The Vizio M51ax-J6 supports all of the audio formats that we test for via ARC. It supports Dolby Digital content, which is the most commonly found surround sound format. It also supports lossless and object-based surround formats like Dolby Atmos.

Update 10/20/2021: We received feedback from a user who experienced issues playing LPCM content over Apple TV and Xbox. However, we weren't able to replicate this phenomenon in our tests. We confirmed that the bar can playback 5.1 PCM.

The Vizio M51ax-J6 has incredible audio format support via Full HDMI In. It supports surround sound formats commonly found on streaming platforms and Blu-ray discs like Dolby Digital and DTS.

The Vizio M51ax-J6 also supports both Dolby Digital and DTS content via Optical. You can often find these formats on streaming platforms and Blu-ray discs.

Update 02/16/2022: Thanks to community input, we confirmed that updating the bar to firmware version 1.3.0.7 improves the bar's latency performance. We've updated our results accordingly.

The Vizio M51ax-J6 has an excellent latency performance. It has fairly low latency via ARC, Optical, and Full HDMI In, so there's no delay between the audio you hear and the video you see. Some apps and TVs compensate for latency differently, though, so your real-world experience can vary.

This soundbar can passthrough the highest bandwidth signals. When connected between your PC and your TV, text on the screen appears clear and crisp.

The Vizio M Series M51ax-J6 only supports Bluetooth connectivity, so you can wirelessly stream audio from mobile devices to the bar over this connection.

There's a set of vertical lights on the left side of the bar that flash different patterns depending on the settings you adjust. It also displays the volume level. Also, you get audio feedback when switching between the different preset modes and inputs.

Several physical buttons on the top of the bar let you power it on/off, change the input, enter Bluetooth pairing mode, and adjust the volume.

The remote is fairly simple and lets you control all the bar's settings, including the volume and the EQ preset.

This soundbar doesn't have built-in voice assistant support. You can plug in a voice assistant-enabled device like an Amazon Echo using the AUX VA In port. However, since this requires purchasing a third-party device, we don't test for it.