soundbars · Head-to-head
Polk Audio Signa S4 vs ZVOX AV157
The short answer
Polk Audio Signa S4 comes out ahead overall with 7.4/10 against 7.0/10 for the ZVOX AV157. Polk Audio Signa S4 is stronger on dialogue clarity, ease of setup & use for seniors and overall sound quality. ZVOX AV157 is stronger on dialogue boost range & controls and safety, energy & repairability.
- Choose the Polk Audio Signa S4 if: Families who want movie-night bass and Atmos but still need a real center channel and adjustable voice lift.
- Choose the ZVOX AV157 if: Hard-of-hearing viewers whose older TV has only optical or headphone outputs.
Scores by criterion
| Criterion | Polk Audio Signa S4 | ZVOX AV157 |
|---|---|---|
| Dialogue clarity | 8.3Lab-tested center channel (RTINGS). | 7.5Older TechHive praise, offset by TechRadar's 'unnatural' remark. |
| Dialogue boost range & controls | 7.03 VoiceAdjust levels plus Night Mode. | 8.512 levels plus Output Leveling. |
| Ease of setup & use for seniors | 7.0HDMI ARC/CEC and no app, but a sub to place and power. | 6.5Single cable, but a separate remote is required. |
| Overall sound quality | 7.5Atmos with a sub, but RTINGS says it lacks deep bass. | 4.5Single-purpose small speaker. |
| Value | 6.8$449 is fair for a 3.1.2 system. | 6.5$199.99, close to the HDMI-equipped AV835. |
| Safety, energy & repairability | 5.0Neutral: no parts or refurbishment evidence found. 2021 design, still sold new. | 8.0Replacement power supply and remotes, renewed units and a 60-day trial. |
Specifications
| Spec | Polk Audio Signa S4 | ZVOX AV157 |
|---|---|---|
| Exact evaluated bar, subwoofer and surround configuration | — | Single AccuVoice AV157 speaker bar; no subwoofer or surrounds |
| Workflow type | — | Standalone single-box TV speaker |
| Dialogue feature | VoiceAdjust | AccuVoice + SuperVoice |
| Exact US model and regional suffix | — | AV157 |
| Dialogue enhancement levels | 3 levels | 12 levels |
| Soundbar width | — | 432 mm |
| Dedicated center channel / speech driver | Yes | No |
| Soundbar height | — | 86 mm |
| Automatic volume leveling | — | Yes |
| Soundbar depth | — | 74 mm |
| Channel configuration | 3.1.2 | — |
| Meets editorial 800-mm width and 80-mm height filter | — | No |
| Dolby Atmos | Yes | No |
| Separate subwoofer included | Yes | No |
| HDMI ARC/eARC | Yes | No |
| Full HDMI source inputs excluding ARC/eARC return port | — | 0 ports |
| Optical input | Yes | Yes |
| Bluetooth | Yes | No |
| Width | — | 17 in |
| Physical remote, TV remote, account and app requirements | — | Included remote; no app; mode switch by long press (Digital Trends) |
| Observed direct manufacturer selling price | — | 199.99 USD |
| Verified manufacturer list price, not assumed from a crossed-out reference | — | 249.99 USD |
| Listing, indexed listing, cart, delivery or conflicting-render status | — | zvox.com $199.99 with 60-day trial; Amazon $199.99 from third-party seller (live) |
| Manufacturer direct home-trial period | — | 60 days |
Polk Audio Signa S4
Pros
- Dedicated center channel
- Three-level VoiceAdjust raises voices only
- Night Mode lifts speech and cuts bass
- Wireless subwoofer included
- Dolby Atmos and Bluetooth
Cons
- Lacks deep low bass, and surround is unimpressive
- Subwoofer needs a second power outlet
- Older design; a successor model exists
- Fewer dialogue levels than the ZVOX bars
A balanced choice for families. It gives up some simplicity for better movie sound while still treating dialogue seriously.
Full Polk Audio Signa S4 review →ZVOX AV157
Pros
- Works with optical or 3.5mm TVs
- 12 voice-boost levels
- Output Leveling for ads
- Replacement power supplies, remotes and renewed units sold
- Compact size
Cons
- No HDMI, so the TV remote cannot control it
- Voices can sound unnatural at high boost
- Weak for music and movies
- Needs a second remote
A narrow but useful product. It is best for older TVs, where it can make a real difference to speech.
Full ZVOX AV157 review →Both products are part of our guide The Best Soundbars for Dialogue Clarity and Seniors of 2026, where you can see every pick, how we score and current prices from each retailer.