Polk S15 vs S20 Bookshelf Speakers: Choose the Right One

Polk Audio has always strived to build a legacy with its top-performing home theater sound systems including floor-standing and bookshelf speakers. This review dives deeper into more details about Polk’s latest signature series – Polk S20 vs S15. But before we get into that….

What are bookshelf speakers?

As the name implies, bookshelf speakers are specially designed for placement on a table, shelf, or other elevated surfaces. Bookshelf speakers deliver quality sound despite their size. And there’s more. Whether you need a speaker for your music or movies, Polk has something in store for you.

The Polk S20 and S15 Bookshelf signature series speakers have a sleek design and a long-lasting build. The S15 speakers offer exceptional audio fidelity and top-notch sound quality. On the other hand, the S20 bookshelf speakers are best known for their clean and deep bass accompanied by a better low-frequency response than the S15 compact bookshelf speaker.

Both Bookshelf Signature Series speakers offer incredible performance from the packed features.

General Specs Comparison

Before we get into the unique features of each speaker, let’s first get an overview of the general specs of S20 vs S15 speakers.

Product TitlePolk S15Polk S20
Mounting OptionsKeyhole availableNot Available
Frequency Response50Hz – 40kHz39Hz – 40kHz
Amplifier Power20 – 100 watts per channel20 – 125 watts per channel
Dimensions10.2 x 7.5 x 12 inches13.8 x 8.5 x 14.8 inches
Weight13 Pounds17 Pounds
Enclosure typeBass ReflexBass Reflex
Cabinet FinishNon-resonant Meddite MDF constructionNon-resonant Meddite MDF construction
Woofer’s Driver ConeMica-reinforced polypropylene materialMica-reinforced polypropylene material
Woofer’s size5.25 inches6.5 inches
Amplifier Power20-100 watts20 – 125 watts
Speaker Design2-way2-way

Polk Audio Signature S15 Bookshelf Speaker Review

Polk S15 was designed and engineered in the USA to improve your surround sound listening experience. From what we’ve seen, the S15 speakers aim to uphold Polk’s legacy.

Below is a summary of the Polk Signature features:

Hi-Res Audio Performance

The speakers’ cabinet features a one-inch high-resolution Terylene dome tweeter that reproduces frequencies to a maximum of 40000 HZ. This delivers clearly detailed and smooth high frequencies. The speaker also comes with a 5-1/4-inch Dynamic Balance woofer that produces mid-range sounds for realistic reproduction of vocals.

Timbre Matched

Timbre-matched speakers are speakers that reproduce sounds in the same way all the time due to identical tonal qualities. Tonal quality is the sound traits of music tones, notes, or sounds that differentiate between vocals and musical instruments in sound production.

The Polk audio S15 speakers are timbre-matched with other Polk center channels, floor-standing speakers, and bookshelf speakers. Therefore, providing a blending effect for the speakers in your multi-channel systems.

Versatile Options for Home Theater Configurations

The Polk audio S15 supports DTS/Dolby surround technologies and the latest Hi-Res audio files, which bring out realistic vocals and instruments. The speakers are flexibly used as front or surround speakers in any home theater setup or a simple stereo configuration to give you a better audio experience.

So, worry not if you have 2.1, 3.1, or 5.1 sound systems because Polk has got you covered.

Reduced Sonic Interference

The mica-reinforced polypropylene cones, high-temperature Conex fiber spiders, and ceramic motor structures allow you to get augmented linearity, deep bass, and enhanced dynamic mid-range by minimizing sound distortion.

Power Port Deep Bass Technology

Polk’s power port deep bass technology ensures that the speaker’s rear side delivers quality and punchy lows. The plastic baffle broadly spreads the low frequencies from the speakers to crank your speakers with oomph from an extended bass response of 3dB.


  • The non-resonant Meddite MDF build helps to achieve a life-like sound experience.
  • There are better mounting options for the speaker using a keyhole Hanger.
  • The polypropene midrange drivers enhance the sound quality and durability while minimizing distortion.
  • The dome tweeters help to get a realistic reproduction of vocals and instruments.
  • The dynamic balance acoustic array ensures you get rich and full-range sounds.


  • It needs to be powered by an amplifier because it’s a passive speaker.
  • Performance reduces for frequencies below 50Hz.

Polk Audio Signature S20 Bookshelf Speaker Review

The Polk S20 speaker is an upgrade of the S15, loaded with extra features that guarantee exceptional sound performance. Here are the Polk audio S20 Bookshelf speakers features worth consideration:

Quality Cabinet Design

The cabinet of the Polk audio S20 has a clear finish that gives it a futuristic and stylish look. The non-resonant Meddite MDF build has thick baffles and extra bracing to reduce sonic interference, thus delivering a life-like music experience. The firm, acoustically inert, and rigid enclosure provides minimal audio coloration by reducing internal standing waves in the speakers.

Dynamic Balance (Acoustic Array)

The Polk audio S20 speaker prides itself on having a state-of-the-art dynamic balance. This technology examines the mechanical and electro-acoustic system of your S20 speakers for enhanced material selection and efficient geometry. And, it also locates underlying issues that may curtail speaker performance before the speaker is released to the market.

Two-Way Speaker Design Crossover Array

This feature is designed to turn your room into a theater for your movies. The two-way crossover array eliminates the need to find the “sweet spot”. You can finally enjoy a cinematic experience from any location in your living room.

Turbulence-Smoothing Diffuser

The turbulence-smoothing diffuser transitions air from the S20 bookshelf speakers to your listening location to produce sounds with minimal distortion. You always get the best sound quality for TV, movies, and music.


  • Anti-diffraction magnetic grill helps to reduce sonic interference.
  • The Gold-plated five-way binding posts help to achieve direct speaker connection.
  • Compatible with numerous surround sound technologies.
  • Highly responsive to lower frequencies (39Hz).
  • The speakers are timbre-matched to offer blending effects in your home theater systems.
  • The Terylene dome tweeters have curvilinear formers to minimize the speaker’s resonance.


  • Requires more space to fit this speaker.
  • It needs to be powered by an amplifier because it’s a passive speaker.

Polk S20 vs S15 Bookshelf Signature Speakers – Final Verdict

Both the Polk S20 and S15 speakers have a solid and rigid cabinet finish to deliver top-quality sound for a long time. The Bass reflex enclosure is enhanced by the Power port technology. Therefore, you can now enjoy clean and deep bass from any of these dual Polk speakers.

Polk S15 vs S20

However, the Polk signature S15 compact bookshelf speakers are perfect for audio lovers who need excellent sound quality for frequencies above 50Hz. Additionally, it only weighs 13 pounds, making it portable, and a good fit for smaller shelf space than the 17lbs Polk S20 Bookshelf speakers.

On the other side, the Polk audio signature S20 speakers deliver cleaner and deeper bass than the S15 speakers. Its low-frequency response of 39Hz to 40kHz allows the speaker to effectively produce sound from a wide range of frequencies effectively.

If you need a bookshelf speaker that delivers quality sound for your small living room at a lower price, you should probably get the Polk audio signature S15 speakers. However, if you need the bass coming out of your speakers to give your movie a cinematic experience, you may look at Amazon for Polk audio signature S20 today.

Avatar for Jamie K. Martin

Jamie K. Martin holds a degree in Audio engineering from Husson University, Bangor. Martin spends most of his time testing and trying the technology he writes about to ensure that he provides first-hand information to our customers from all walks of life.

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