In this review, we will be comparing Monitor XT12 and S8, two Powered Subwoofer speakers from Polk Audio and Audioengine. Being Powered subwoofers, they both have built-in amplifiers so you don't need an external power amp or an integrated amp to power them. Let's have a brief look at the main features of Polk Monitor XT12 and Audioengine S8 first before getting into our more detailed comparison.
The sections below take each area in turn: driver and amplifier, frequency response, physical size and connectivity.
Drivers
The efficiency of a subwoofer is directly proportional to the total radiating are squared hence the woofer quantity and diameter.Both Polk Monitor XT12and Audioengine S8 have a single woofer setup however the Polk Monitor XT12's woofer is 12-inch whereas the Audioengine S8 features a 8-inch woofer.
Frequency Response
Monitor XT12 has a frequency range of 24-160 Hz whereas S8 has a frequency range of 27-180 Hz. With a minimum frequency of 24Hz, the Monitor XT12 can go slightly deeper then the S8's min frequency of 27Hz.
Below graphs depict how these two speakers compare with the max, min and average values of the Min and Max Frequencies of other speakers in the Subwoofer class in our database.
Low Frequency
Subwoofer Speakers
High Frequency
Subwoofer Speakers
Cabinet Type
Both Polk Monitor XT12 and Audioengine S8 have Bass Reflex type cabinets. Bass Reflex type subwoofers (aka Ported, Vented or Reflex Port) have enclosures that uses a port, hole or vent cut into the cabinet. Ported designs are generally more efficient than the Sealed designs.
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 Monitor XT12's and Audioengine S8's external dimensions. Polk Monitor XT12 has external dimensions of 418.0 x 408.0 x 485.0mm (16-7/16inch x 16-1/16inch x 19-1/16inch) whereas Audioengine S8 has external dimensions of 334.0 x 293.0 x 337.0mm (13-1/8 x 11-1/2 x 13-1/4inch).
Polk Monitor XT12 is clearly the larger of the two speakers. Its body is 115mm wider, 84mm taller and 148mm deeper than Audioengine S8.
Below you can see the front view size comparison of Polk Monitor XT12 and Audioengine S8 in scale.
Comparison image of Polk Monitor XT12 and Audioengine S8 Size and External Dimensions
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 Monitor XT12 is approximately 1978.8cm2 / 306.7inch2 and base area of the Audioengine S8 is approximately 987.4cm2 / 153.0inch2. The Monitor XT12 requires 100% more surface area than the S8 which gives it a small disadvantage on placement in tight spaces.
Weight Comparison The weight of a subwoofer may become an important factor if you need to move and reposition the unit often to find the optimal positioning, also known as 'Subwoofer Crawling'. The Polk Monitor XT12 weighs 17.73kg / 39lbs and the Audioengine S8 weighs 13.64kg / 30lbs. This makes the Monitor XT12 30% heavier than the S8.
Here is a comparison of how Monitor XT12 and S8's weights compare with the average, max and min weights in Powered Subwoofer class.
Weight
All Subwoofer Speakers
What's in the Box of Polk Monitor XT12?
Here are the items that are included inside the box of Monitor XT12:
- Black powered subwoofer
- 6.5-feet AC power cord
- Grille
- Owners Manual
- Online registration card
What's in the Box of Audioengine S8?
Here are the items that come with the S8:
- Powered subwoofer
- 6-feet AC power cord
- 6.5-feet Stereo RCA cable
- 6.5-feet Stereo minijack audio cable
- Cloth subwoofer bag
- Cloth cable bag
- Quick Start Guide
- Audioengine brochure
 Woofer Size |
12 inches
vs
8 inches
|
Larger woofer |
| Low Frequency Response |
24 Hz
vs
27 Hz
|
Generates deeper bass |
 High Frequency Response |
180 Hz
vs
160 Hz
|
Generates higher frequency |
 Height |
334mm
vs
418mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
987cm2
vs
1978cm2
|
Takes less floor space |
 Price per pair* |
349USD
vs
399USD
|
costs less (*prices may change depending on the seller, location and time) |
Size, drawn to scale
Both subwoofers and both views share one scale, so everything here is directly comparable. Hover a box for its dimensions.
One scale for both, standing on the same floor and pushed back to the same wall, so the bigger one visibly takes more of the room.
Polk Monitor XT12 needs about 100% more floor area. Polk Monitor XT12 stands 148mm further into the room. Polk Monitor XT12 is 84mm taller.
| General |
Polk Monitor XT12 |
Audioengine S8 |
| Brand |
Polk Audio |
Audioengine |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
50 watts |
125 watts |
| Frequency Response |
24-160 Hz |
27-180 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
50-watt RMS |
125-watt RMS |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
12" |
8" |
| Woofer Composition |
Bi-laminate paper |
Treated paper |
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Firing Direction |
front |
bottom |
Physical Specs |
|
|
| Height |
418.0mm (16.5") |
334.0mm (13.1") |
| Width |
408.0mm (16.1") |
293.0mm (11.5") |
| Depth |
485.0mm (19.1") |
337.0mm (13.3") |
| Weight |
17.73kg (39lbs) |
13.64kg (30lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Grille |
Yes |
n/a |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
3 Years |
3 Years |
| Labor Warranty |
3 Years |
3 Years |
Two quite different sizes of subwoofer. Room volume decides this more than anything else on the page: a big driver in a small room is wasted, and a small one in a large room is worked to death.
| Area | Better | Why |
|---|
| Bass depth | A | Polk Monitor XT12 goes deeper - 24Hz against 27Hz. A real difference, though most music has little content below 27Hz. |
| Amplifier power | B | Audioengine S8 has the bigger amplifier - 125W against 50W RMS, about 4dB more on tap. In a large room that is headroom before the DSP starts limiting. |
| Driver area | A | Polk Monitor XT12 moves more air: 12" against 8" is 2.25x the cone area, not the 1.5x the diameters suggest. More area means the same output with less excursion, and less distortion with it. |
| Enclosure | evenly matched | Both are ported designs, so they roll off in much the same way. |
| Speaker-level inputs | A | Polk Monitor XT12 takes a speaker-level connection as well as line level. That is what lets it work with an integrated amplifier or a vintage receiver that has no subwoofer output at all. |
| Driver placement | depends | Polk Monitor XT12 fires front and Audioengine S8 fires down. A down-firing driver is more forgiving of a grille-less look and of a hard floor; a front-firing one is the safer choice on a thick carpet or a suspended timber floor. |
| Cabinet size | depends | Audioengine S8 is about 60% smaller by volume. In a subwoofer that is a real trade rather than a preference: box volume is how you get output low down without a bigger amplifier. |
| Price | B | Audioengine S8 costs less - $349 against $399, about 13% less. |
A Polk Monitor XT12 B Audioengine S8
depends neither is better in the abstract - it turns on your room, your system or how you will use them. Only specs published for both subwoofers are judged; anything missing on either side is left out rather than guessed.
Which should you choose?
The usual trade-off: Polk Monitor XT12 measures better, Audioengine S8 costs about 13% less. In a normal room, placement will make a bigger difference than the gap between these two. Check your amplifier first: if it has no subwoofer or preamp output, Polk Monitor XT12 is the only one of these two you can connect at all. If placement is the constraint - a corner, behind a sofa, under a desk - Audioengine S8 is the one that will actually go there, and a well-placed small subwoofer beats a badly-placed big one every time.
One thing outweighs everything above: where the subwoofer stands. Room modes can add or remove 10dB or more at a given seat, which is far larger than any difference on this page. Before spending more, try the sub in two or three positions - the crawl test, where you put it in the listening seat and crawl the room to find where the bass sounds best, costs nothing and usually beats an upgrade.