Polk S55 vs Polk S15 Comparison

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Polk S55

Passive Floor-standing | 32-40k Hz

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Polk S15

Passive Bookshelf | 50-40k Hz

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Polk S55

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Polk S15

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Polk S55

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Polk S15

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Polk S55 vs Polk S15 Speaker Comparison

In this review, we will be comparing two different types of speakers by Polk Audio. Polk Audio Signature S55 is a Floor-standing speaker whereas the S15 is a Bookshelf speaker.

Let's have a brief look at the main features of Polk S55 and Polk S15 first before getting into our more detailed comparison.

Key Specs	Polk S55	Polk S15
Design	2-way	2-way
Tweeter	1" Dome	1" Dome
Woofer	2 x 6.5" Mica-reinforced polypropylene	5.25" Mica-reinforced polypropylene
Frequency response	32-40k Hz	50-40k Hz
Sensitivity	90 dB	88 dB
Impedance	8 ohms	8 ohms
Power range	20-200 watts	20-100 watts
Weight	20.00kg / 44lbs	5.90kg / 13lbs
Dimensions (H x W x D)	41-9/16" x 11-3/4" x 12-3/8" 1056.0 x 299.0 x 315.0mm	12.0" x 7.4" x 10.2" 304.8 x 190.0 x 260.4mm

S55 and S15 are members of Polk Audio's Signature S series of speakers. Below you can find the loudspeakers from this series.

Polk Audio Signature S Series History

Model	Body	Frequency	Sensitivity	Impedance	Woofer
Polk S60	Floor-standing	26-40k Hz	90 dB	8Ω	3 x 6.5"
Polk S20	Bookshelf	39-40k Hz	88 dB	8Ω	1 x 6.5"
Polk S15	Bookshelf	50-40k Hz	88 dB	8Ω	1 x 5.25"
Polk S55	Floor-standing	32-40k Hz	90 dB	8Ω	2 x 6.5"
Polk S10	Bookshelf	67-40k Hz	87 dB	8Ω	1 x 4"
Polk S50	Floor-standing	33-40k Hz	89 dB	8Ω	2 x 5.25"

What size room are the Polk S55 and Polk S15 speakers good for?

The size of the room in which you are planning to use these loudspeakers is an important decision factor. Here we have compared their suitability to various sizes of environments considering their size and max power parameters:

Listening Environment*	Polk S55	Polk S15
Near-field	Bad	Average
Small Room	Poor	Good
Mid-size Room	Good	Average
Large Room	Good	Poor
Very Large Room	Poor	Bad

(* Approximate Room sizes: Small < 100sq. ft / 9 m², Mid-size: 100-220 sq. ft / 9-20 m², Large 220-400 sq. ft / 20-36 m², Very Large: > 400 sq. ft / 36 m². Average Floor Height: 9" / 2.7m. Typical room sizes differ from country to country, and the actual listening experience changes depending on floor height, room shape, surface materials, listening position, speaker locations, etc.)

The sections below take each area in turn: drivers, frequency response, physical size and what you get in the box.

**This post contains affiliate links, and we will be compensated if you make a purchase after clicking through our links. As an Amazon Associate I earn from qualifying purchases.

Drivers

Both S55 and S15 are 2-way speakers.

Polk S55

Polk S15

TweeterWoofer

Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.

Driver	Polk S55	Polk S15
Driver Setup	2-way	2-way
Tweeter	1-inch	1-inch
Midrange	-	-
Woofer	2 x 6.5-inch	1 x 5.25-inch

S55 features a 1" Terylene Dome Tweeter and 2 x 6.5" Mica-reinforced polypropylene Woofer with a Crossover frequency at 2500Hz. On the other hand, the S15 features a 1" Terylene Dome Tweeter and 1 x 5.25" Mica-reinforced polypropylene Woofer with a Crossover frequency at 2500Hz.

Frequency Response

S55 has a frequency range of 32-40k Hz whereas S15 has a frequency range of 50-40k Hz. With a minimum frequency of 32Hz, the S55 can go significantly deeper on the low side and provide stronger bass compared to the S15's min frequency of 50Hz.

The graph below depicts how these two speakers compare with the max, min and average Low Frequency values of other speakers in the Floor-standing class in our database.

Low Frequency

Floor-standing Speakers

S55

S15

Min

Average

Median

Neither pair reaches down to 20Hz, the usual definition of full-range, which is normal for speakers of this size. If you want the bottom octave for movies or bass-heavy music, add a subwoofer to whichever you choose. Visit our Powered Subwoofers section to find out more about the available options.

Impedance and Sensitivity

S55 and S15 have the same Impedance of 8 ohms but where they differ is the sensitivity levels. S55 sensitivity is rated at 90 dB and the S15's is at 88 dB. This 2 dB difference makes the Polk S55 a more sensitive speaker compared to Polk S15, hence will play louder with the same amount of watts.

Sensitivity

Floor-standing Speakers

S55

S15

Min

Average

Median

Power Range

Power range is the range of input power in watts RMS that a loudspeaker is designed to handle. Staying within that range gives nominal performance; driving the speaker beyond its maximum wattage can damage it.

S55 can handle a max power of 200 watts RMS, whereas S15 has a max power handling value of 100 watts RMS, 100 watts less than the S55.

Note that higher power handling does not make a speaker louder: that depends mainly on sensitivity and impedance. The calculator below shows how loud each of these actually plays on a real amplifier.

Which plays louder on your amplifier?

Starting with a popular amplifier — change it to the one you own, or any you are considering, and watch both numbers move.

Amplifier — change this

Distance

Playing as

Polk S55

Polk S15

Input Type and Bi-Amping / Bi-Wiring

S55 features 5-way post posts which make bi-amping or bi-wiring possible. S15 has a Pair of Binding Posts - Gold Plated which doesn't feature bi-amping/bi-wiring.

Polk S55's 5-way post terminals allows Bi-amping or bi-wiring

Cabinet Type and Port Position

S55 has a bottom firing port whereas S15 has a rear firing ports. Polk S55's bottom-firing port gives more flexibility in placement in regards to proximity to walls compared to Polk S15 with its rear-firing port.

Polk S55 Port

Physical Specs

The size of a speaker can sometimes be an important decision factor due to space constraints or in some cases purely for esthetic reasons. In this section, we are going to compare Polk S55's and Polk S15's external dimensions. Polk S55 has external dimensions of 1056.0 x 299.0 x 315.0mm (41-9/16 x 11-3/4 x 12-3/8inch) whereas Polk S15 has external dimensions of 304.8 x 190.0 x 260.4mm (12.0 x 7.4 x 10.2inch).

Polk S55 is clearly the larger of the two speakers. Its body is 109mm wider, 751.2mm taller and 54.6mm deeper than Polk S15.

Base Surface Area Comparison
Base surface area of a loudspeaker may become a determining factor when the space in your room or desk is limited. The base surface area of the Polk S55 is approximately 941.9cm² / 146.0inch² and base area of the Polk S15 is approximately 494.8cm² / 76.7inch². The S55 requires 90% more surface area than the S15 which gives it a small disadvantage on placement in tight spaces.

What's in the Box of Polk S55?

Here are the items that are included inside the box of S55:

Floorstanding loudspeaker
Grille (attached)
4 Feet (pre-installed)
Owners Manual
Online Product Registration

What's in the Box of Polk S15?

Here are the items that come with the S15:

2 Bookshelf loudspeakers
2 Grille (attached)
8 Self-adhesive rubber feet
Wall-mount template
Owners Manual
Online Product Registration

Reasons to choose Polk Audio Signature S55 over Polk Audio Signature S15

Max Input Power	200 watts vs 100 watts	Handle more power from your amplifier
Sensitivity	90 dB vs 88 dB	Play louder with same amount of amplification power
Woofer Size	6.5 inches vs 5.25 inches	Larger woofer
Number of Woofers	2 vs 1	More woofers
Low Frequency Response	32 Hz vs 50 Hz	Generates deeper bass
Bi-Amping and Bi-Wiring	Yes vs No	Allows bi-amping and bi-wiring connections

Reasons to choose Polk Audio Signature S15 over Polk Audio Signature S55

Mounting Bracket	Yes vs No	Allows mounting on walls
Height	304mm vs 1056mm	Easier to fit in smaller spaces
Base Surface Area	494cm² vs 941cm²	Takes less floor space
Price per pair*	259USD vs 658USD	costs less (*prices may change depending on the seller, location and time)

Polk S55 vs Polk S15 Specs Table

Detailed comparison of specifications

General	Polk Audio Signature S55	Polk Audio Signature S15
Brand	Polk Audio	Polk Audio
Speaker Type	Floor-standing speaker	Bookshelf speakers
Power Range	20-200 watts	20-100 watts
Sensitivity	90 dB	88 dB
Impedance	8 ohms	8 ohms
Frequency Response	32-40k Hz	50-40k Hz
Drivers
Woofer Quantity	2	1
Woofer Size	6.5"	5.25"
Woofer Composition	Mica-reinforced polypropylene	Mica-reinforced polypropylene
Woofer Surround Material	Butyl rubber	Butyl rubber
Tweeter Size	1"	1"
Tweeter Type	Dome	Dome
Aimable Tweeter	No	No
Midrange Driver	No	No
Crossover Frequency	2500Hz	2500Hz
Firing Direction	bottom	rear
Physical Specs
Height	1056.0mm (41.6")	304.8mm (12")
Width	299.0mm (11.8")	190.0mm (7.5")
Depth	315.0mm (12.4")	260.4mm (10.3")
Weight	20.00kg (44lbs)	5.90kg (13lbs)
Enclosure	Bass Reflex	Bass Reflex
Finish	Meddite MDF	Meddite MDF
Available Colors	Black	Black, Walnut, Brown Walnut
Mounting Bracket	No	Keyhole
Recommended Stand Height	n/a	24-30"
Grille	Yes	Yes
Moisture Resistancy	No	No
Connections
Biamp Inputs	Yes	No
Other
Parts Warranty	5 Years	5 Years
Labor Warranty	5 Years	5 Years

Verdict

Siblings in Polk Audio's Signature S series, so they share a family sound. It comes down to size, output and price.

Area	Better	Why
Bass	A	Polk S55 digs deeper - 32Hz against 50Hz.
Amplifier needs	A	Polk S55 is more sensitive (90dB vs 88dB), so it goes louder on the same amplifier.
Headroom	A	Polk S55 takes more power (200W vs 100W) - more in hand in a big room.
Size	depends	Polk S15 is easier to place; Polk S55 is bigger, which usually goes with fuller bass. Your room decides.
Type	depends	A Passive Floor-standing against a Passive Bookshelf - a different job rather than a better one.
Expandability	A	Polk S55: bi-amping.
Price	B	Polk S15 is cheaper - $259 against $658, about 61% less; arguably a different class.

A Polk S55 B Polk S15
depends neither is better in the abstract - it turns on your room, placement or how you will use them. Only specs published for both speakers are judged; anything missing on either side is left out rather than guessed.

Which should you choose?

The usual trade-off: Polk S55 measures better, Polk S15 costs about 61% less. Whether that gap is worth the money is the call only you can make - and in a normal room it is often smaller than the numbers suggest. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 50Hz anyway, which makes the cheaper Polk S15 much easier to justify. Match it to your room: we rate Polk S55 the better fit for a mid-size room and a large room, and Polk S15 for near-field listening and a small room.

And remember what a spec sheet cannot show: how each looks in your room and whether the finish suits it, what dealer support and warranty are like where you live, and how they actually sound to you. If you can hear them first - ideally with your own music - that will tell you more than any number above.