Polk Audio Signa S4 Soundbar Review

The Polk Audio Signa S4 has a pretty similar design to the Polk Audio Signa S2. Both bars are mostly plastic, with fabric covering the front of the bar. On the S4, fabric covers the entire top of the bar, too.

The sub looks a bit different than the one that comes with the Polk Audio Signa S2. It's mostly melamine, and unlike the S2, there's no fabric on the sub. It also sits on four pegs, and the port is underneath.

Unlike the Polk Audio Magnifi Max AX SR, this bar doesn't include satellites.

The Polk S4 is quite long, so it doesn't fit between the legs of a 55" TV stand. That said, it's not very tall, so it doesn't obscure your TV screen.

The subwoofer is roughly the same size as a desktop computer. It connects to the soundbar wirelessly, handy for placing it wherever you want in your room.

The Polk Audio Signa S4 has a satisfactory build quality. The bar itself is mostly plastic, which doesn't feel very premium. However, the fabric on the front and the top of the bar is tight and thick, so it doesn't seem like it rips easily. The subwoofer's melamine build feels more solid than the Polk Audio Signa S2, too.

• User Guides
• Remote with 2x AAA batteries
• 2x wall-mount spacers
• 2x power cables (4.9 ft / 1.5m)
• Optical cable (5.9 ft / 1.8m)
• HDMI cable (4.9 ft / 1.5m)

The Polk Audio Signa S4 has a satisfactory stereo frequency response. Its sound profile is V-shaped, meaning that there's a touch of extra boom in the bass and some extra brightness in the treble that makes vocals and lead instruments sparkle. Dialogue in movies and TV shows is clear and accurate, thanks to the balanced mids. If you like to listen to bass-heavy genres, you'll notice the lack of low-bass since you don't feel the deep thump and rumble on these tracks.

The Polk Audio Signa S4 has a bass adjustment feature to help you customize its sound. When you set it to '-3', the sound profile is more neutral and balanced. Vocals and lead instruments are clear and detailed in the mix. There's still a little extra punch in the mid-to-high bass range; it's less noticeable than with its default sound. That said, bass adjustment features can't make up for the lack of low-bass, so you're still missing the deep rumble in bass-heavy music genres.

The Polk Audio Signa S4 has a decent soundstage. It's perceived to be about as wide as the bar itself, but it doesn't have any tricks to make it seem wider than that. On the upside, it gives a good sense of height, even with music, so the soundstage seems to reach up over your TV screen. The focus is good, too. For example, if you're listening to an orchestra, each instrument seems to come from an accurate, pinpoint location in the soundstage.

The Polk Audio Signa S4 has decent stereo dynamics. It can get loud enough to fill an average-sized living room with sound. If you have a larger space or want to crank up the volume for parties, it doesn't get loud enough for these uses. Fortunately, when you push it to max volume, there isn't much compression.

The Polk Audio Signa S4 has a good center channel performance. It's a 3.1.2 setup, meaning that it comes with a discrete center channel. This helps anchor voices to a pinpoint location in the soundstage, so dialogue is clearly and accurately reproduced.

The Polk Audio Signa S4's surround performance is poor, but that's normal for 3.1 soundbars. The bar doesn't come with dedicated surround speakers. Instead, it has to downmix surround sound into stereo to play it. Unfortunately, this doesn't sound as immersive. Audio seems like it's coming from speakers placed in front of you rather than from speakers placed all around you.

The Polk Audio Signa S4 has a middling Atmos performance. There are two up-firing drivers built into the bar itself, which ricochet sound off the ceiling to create the illusion of height. The bar does a good job simulating height, meaning drones seem to fly overhead from clear and accurate locations around you. The lack of low-bass is noticeable, especially with action-packed scenes and high-intensity explosions. It doesn't provide the same immersive feeling as more premium setups like the Bose Smart Soundbar 900 or the Sony HT-A9. But, ultimately, it offers a comparable performance to other Atmos bars in this price range, like the Sonos Beam (Gen 2) and the Vizio M Series M512a-H6.

The selection of sound enhancement features for the Polk Audio Signa S4 is pretty limited. As expected with bars in its price range, you don't find premium sound enhancement features like room correction. There's a dialogue enhancement feature - which Polk calls VoiceAdjust - and it lets you choose between three different volume levels for the voices in your audio. The Night Mode feature is ideal for watching TV at night since it lowers the bass and increases the dialogue's volume to help you hear every word without bothering anyone around you. However, if you want to customize its sound, there aren't many options besides its bass adjustment feature and its two EQ presets: Music and Movie.

There's a pretty limited selection of inputs on the Polk S4. You can connect the bar to your TV with its optical or HDMI ARC inputs. You can also play music on the bar from other sources using its 3.5mm AUX input or its USB input for flash drives. However, you won't find an HDMI In port for video passthrough.

The Polk Audio Signa S4 has excellent audio format support via ARC. It supports some of the most common surround sound formats, including Dolby Digital, and lossless and object-based formats like Dolby Atmos. Unfortunately, there's no support for DTS content.

Over Optical, the Polk Audio Signa S4 supports Dolby Digital, the most common surround sound format used on Blu-rays and streaming platforms. There's no DTS support, though.

Audio latency over an ARC connection is great. The audio you hear is in sync with the video you see with lots of common audio formats, from Dolby Digital to Dolby Atmos. Some apps and TVs compensate for latency differently, though.

Audio latency is on the higher end over an Optical connection, especially with Dolby Digital content. As one of the most common surround sound formats, you'll likely come across it on many different streaming platforms and Blu-rays. Some apps and TVs compensate for latency differently, but if you have issues, try switching to an ARC connection for better results.

The Polk Audio Signa S4 only supports Bluetooth connectivity. You can wirelessly stream audio from your phone or tablet to the bar over Bluetooth.

There's no display, but you can find a couple of small lights on the front of the bar that change colors, depending on the settings you use. It's green when playing Dolby Digital content and teal with Dolby Atmos. Also, it turns red when an audio format isn't supported.

There are a couple of physical controls on top of the Polk S4. You can use them to power it on/off, change the input, activate Bluetooth, and adjust the volume.

The remote is small and straightforward, providing easy access to all the bar's features. You can adjust the volume, change the input, and add or subtract the amount of bass. The three numbered buttons at the bottom of the remote let you choose between the three levels of dialogue enhancement. Above that, you find the buttons for the Music and Movie EQs as well as the Night Mode feature.