Polk Audio Signa S4 vs ZVOX AV855
The short answer
ZVOX AV855 comes out ahead overall with 8.1/10 against 7.4/10 for the Polk Audio Signa S4. Polk Audio Signa S4 is stronger on overall sound quality. ZVOX AV855 is stronger on dialogue boost range & controls, ease of setup & use for seniors, value and safety, energy & repairability. At current verified prices, the ZVOX AV855 costs about $99.01 less.
- 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 AV855 if: Anyone who struggles to follow TV dialogue on a mid-size or large TV and wants one bar the TV remote controls, with the widest voice-boost range.
Scores by criterion
| Criterion | Polk Audio Signa S4 | ZVOX AV855 |
|---|---|---|
| Dialogue clarity | 8.3Lab-tested center channel (RTINGS). | 8.3Two independent reviews (TechRadar, Home Technology Review) praise the speech lift, but there is no lab test. |
| Dialogue boost range & controls | 7.03 VoiceAdjust levels plus Night Mode. | 8.820 levels plus Output Leveling, the widest range in the pool. ZVOX's FAQ text is inconsistent ('6 modes'), but its spec page says 10+10. |
| Ease of setup & use for seniors | 7.0HDMI ARC/CEC and no app, but a sub to place and power. | 8.5HDMI-ARC/CEC, a remote with large buttons, no app, and a 60-day trial. |
| Overall sound quality | 7.5Atmos with a sub, but RTINGS says it lacks deep bass. | 6.5TechRadar calls it 'a bit boxy' with weak virtual surround. |
| Value | 6.8$449 is fair for a 3.1.2 system. | 7.5$349.99. The AV835 has the same DSP for $100 less, so this is fair rather than outstanding. |
| Safety, energy & repairability | 5.0Neutral: no parts or refurbishment evidence found. 2021 design, still sold new. | 7.5Replacement remotes, power supplies and certified-renewed units are sold. No recall found. |
Specifications
| Spec | Polk Audio Signa S4 | ZVOX AV855 |
|---|---|---|
| Dialogue feature | VoiceAdjust | AccuVoice + SuperVoice |
| Dialogue enhancement levels | 3 levels | 20 levels |
| Dedicated center channel / speech driver | Yes | — |
| Automatic volume leveling | — | Yes |
| Channel configuration | 3.1.2 | — |
| Dolby Atmos | Yes | No |
| Separate subwoofer included | Yes | No |
| HDMI ARC/eARC | Yes | Yes |
| Optical input | Yes | Yes |
| Bluetooth | Yes | No |
| Width | — | 33.7 in |
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 AV855
Pros
- 20 voice-boost levels (10 AccuVoice plus 10 SuperVoice)
- HDMI-ARC lets the TV remote control power and volume
- Output Leveling evens out loud commercials
- Large-button remote
- Replacement remotes and renewed units available, with a 60-day home trial
Cons
- Music can sound somewhat boxy
- No Bluetooth or Wi-Fi streaming
- No Dolby Atmos or DTS:X
- Some owners found the boost less dramatic than expected
The best fit for most viewers who want clearer speech without learning a new system. It trades music quality for dialogue tools, and that is the right trade for this guide.
Full ZVOX AV855 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.