In this review, we will be comparing HD5 and R-51PM, two Powered Bookshelf speakers from Audioengine and Klipsch. Being Powered speakers, 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 Audioengine HD5 and Klipsch R-51PM first before getting into our more
detailed comparison.
| Key Specs | Audioengine HD5 | Klipsch R-51PM |
|---|
| Brand | Audioengine
United States · founded 2005 | Klipsch
United States · founded 1946 |
|---|
| Design | 2-way | 2-way |
|---|
| Built-in amplifier | 100-watt RMS (150-watt peak) | 120-watt RMS (240-watt peak) |
|---|
| Tweeter | 0.75" Soft-Dome | 1.0" Tractrix Horn |
|---|
| Woofer | 5" Aramid | 5.25" Copper-spun IMG |
|---|
| Frequency response | 55-22k Hz | 68-21k Hz |
|---|
| Max depth / sample rate | 24-bit / 192 kHz | 24-bit / 96 kHz |
|---|
| Bluetooth | Built-in 5.0 | Built-in 3.0 |
|---|
| Weight | 5.70kg / 12.5lbs | 4.80kg / 10.6lbs |
|---|
| Dimensions (H x W x D) | 11.125" x 7.1875" x 10.4375"
283.0 x 183.0 x 266.0mm | 13" x 7.0625" x 10.25"
330.2 x 179.4 x 260.3mm |
|---|
The sections below take each area in turn: drivers, frequency response, physical size and what you get in the box.
Drivers
Both HD5 and R-51PM are 2-way speakers.
Audioengine HD5Klipsch R-51PM
TweeterWoofer
Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.
| Driver |
Audioengine HD5 |
Klipsch R-51PM |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
0.75-inch
|
1.0-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 5-inch
|
1 x 5.25-inch
|
HD5 features a 0.75" Silk Soft-Dome Tweeter and 1 x 5" Aramid Woofer. On the other hand, the R-51PM features a 1.0" Aluminum LTS Tractrix Horn Tweeter and 1 x 5.25" Copper-spun IMG Woofer with a Crossover frequency at 1663Hz.
Frequency Response
HD5 has a frequency range of 55-22k Hz whereas R-51PM has a frequency range of 68-21k Hz. With a minimum frequency of 55Hz, the HD5 can go significantly deeper on the low side and provide stronger bass compared to the R-51PM's min frequency of 68Hz.
The graph below depicts how these two speakers compare with the max, min and average Low Frequency values of other speakers in the Bookshelf class in our database.
Low Frequency
Bookshelf Speakers
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.
Cabinet Type and Port Position
Both HD5 and R-51PM have rear firing ports. Rear ported speakers generally need more room between the backside of the speaker and the wall compared to sealed and front/bottom ported speakers. Placing the speakers too close to the walls may cause the bass to sound boomy.
If you are limited in space and can't get the speakers away from the backwall, check our Speakers with Front Firing Ports page.
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 Audioengine HD5's and Klipsch R-51PM's external dimensions. Audioengine HD5 has external dimensions of 283.0 x 183.0 x 266.0mm (11.125inch x 7.1875inch x 10.4375inch) whereas Klipsch R-51PM has external dimensions of 330.2 x 179.4 x 260.3mm (13 x 7.0625 x 10.25inch).
Klipsch R-51PM is 3.6mm narrower and 5.7mm less deeper than Audioengine HD5 but it is also 47.2mm taller.
Size, drawn to scale
Both speakers 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 surface and pushed back to the same wall, so the deeper one visibly sticks out further.
Near-identical footprints. Klipsch R-51PM is 47mm taller.
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 Audioengine HD5 is approximately 486.8cm2 / 75.5inch2 and base area of the Klipsch R-51PM is approximately 467.0cm2 / 72.4inch2. The HD5 requires 4% more surface area than the R-51PM which gives it a small disadvantage on placement in tight spaces.
Weight Comparison The weight of a loudspeaker can become an important factor if you need to move and reposition the unit often. Weight of a speaker can also "sometimes" be an indicator of the rigidity of the enclosure and the quality of the internal components used. The Audioengine HD5 weighs 5.70kg / 12.5lbs and the Klipsch R-51PM weighs 4.80kg / 10.6lbs. This makes the HD5 19% heavier than the R-51PM.
Here is a comparison of how HD5 and R-51PM's weights compare with the average, max and min weights in Powered Bookshelf class.
Weight
All Bookshelf Speakers
What's in the Box of Audioengine HD5?
Here are the items that are included inside the box of HD5:
- Powered speaker
- Passive speaker
- 2 Grilles (pre-installed)
- 6-feet AC power cord
- Remote control (CR2025 battery installed)
- Bluetooth antenna
- 13-feet Speaker cable (banana connectors on each end)
- 5-feet Stereo minijack cable
- 6-feet Stereo RCA cable
- 2 Microfiber speaker bags
- MIcrofiber cable bag
- Quickstart Guide
- Brochure
What's in the Box of Klipsch R-51PM?
Here are the items that come with the R-51PM:
- Powered speaker (right)
- Passive speaker (left)
- 2 Grilles
- 68-inch AC power cord
- Remote control
- 2
 Low Frequency Response |
55 Hz
vs
68 Hz
|
Generates deeper bass |
 High Frequency Response |
22k Hz
vs
21k Hz
|
Generates higher frequency |
 Height |
283mm
vs
330mm
|
Easier to fit in smaller spaces |
 Price per pair* |
549USD
vs
599USD
|
costs less (*prices may change depending on the seller, location and time) |
|
Woofer Size |
5.25 inches
vs
5 inches
|
Larger woofer |
 Base Surface Area |
467cm2
vs
486cm2
|
Takes less floor space |
 USB Port |
USB-B
vs
No
|
USB port adds flexibility |
 RCA Connection |
Yes
vs
No
|
Connection via RCA input |
 Phono Input |
Yes
vs
No
|
Connect your turntable directly |
| General |
Audioengine HD5 |
Klipsch Reference R-51PM |
| Brand |
Audioengine |
Klipsch |
| Speaker Type |
Powered Stereo Speakers |
Powered Stereo Speakers |
| Frequency Response |
55-22k Hz |
68-21k Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
100-watt RMS |
120-watt RMS |
| Watts Peak (Max) |
150-watt RMS |
240-watt RMS |
| Max Bit Depth |
24-bit |
24-bit |
| Max Sample Rate |
192 kHz |
96 kHz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
5" |
5.25" |
| Woofer Composition |
Aramid |
Copper-spun IMG |
| Tweeter Size |
0.75" |
1.0" |
| Tweeter Type |
Soft-Dome |
Tractrix Horn |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
n/a |
1663Hz |
| Firing Direction |
rear |
rear |
Physical Specs |
|
|
| Height |
283.0mm (11.1") |
330.2mm (13") |
| Width |
183.0mm (7.2") |
179.4mm (7.1") |
| Depth |
266.0mm (10.5") |
260.3mm (10.2") |
| Weight |
5.70kg (12.5lbs) |
4.80kg (10.6lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Available Colors |
Black,Walnut,White |
n/a |
| Mounting Bracket |
No |
No |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Aux Inputs |
RCA,3.5mm |
3.5mm, RCA |
| USB Port |
No |
USB-B |
| Phone Input |
No |
Yes |
| Subwoofer Output |
Stereo RCA |
Wired |
| Digital Input |
Optical |
Optical |
| HDMI Input |
No |
No |
| Headphone Jack |
No |
No |
| Ethernet Port |
No |
No |
Other |
|
|
| Parts Warranty |
3 Years |
1 Year |
| Labor Warranty |
3 Years |
1 Year |
No single best speaker here - they are built to different priorities, and the right one depends on your room, your sources and what you listen to.
| Area | Better | Why |
|---|
| Bass | A | Audioengine HD5 digs deeper - 55Hz against 68Hz. |
| Built-in power | evenly matched | Similar onboard amplification (100W vs 120W RMS). |
| Connections | B | Klipsch R-51PM adds phono. |
| Size | depends | Similar cabinet size - neither is easier to fit. |
| Expandability | depends | Audioengine HD5: a sub output; Klipsch R-51PM: a sub output. |
| Price | evenly matched | Much the same money ($549 vs $599 a pair). |
A Audioengine HD5 B Klipsch R-51PM
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 speakers are judged; anything missing on either side is left out rather than guessed.
Which should you choose?
Neither runs away with it - they trade advantages. Let the "depends" rows and your own room settle it. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 68Hz anyway, so judge these on the other rows instead.
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.