Company & Product Overview

Audioengine was founded by two friends who previously worked at companies like Apple, Alesis, Gibson Guitars, and Harmon/Kardon. After working with each other in one capacity or another, they finally came together and formed a brand that would fuse their backgrounds in both groundbreaking technologies and musical instrument building. In 2005, they launched the company’s first powered speaker, and Audioengine was born.

Since then, the company has created a complete line of high-performance audio products that are easy to use and sound great. Audioengine speakers are known for delivering the sound quality of professional studio monitors right to your living room or workspace without the need for a separate stereo receiver to power a pair of passive speakers.

The Audioengine HD4 Powered Bookshelf Speakers, featured in today's review is a premium all-in-one wireless speaker system that is compact and powerful. It sports the latest-and-greatest Bluetooth 5.0 spec and it supports aptX HD too. It accepts audio inputs from a 3.5mm mini-plug or a pair of RCA’s from a turntable or a TV. It allows you to connect a subwoofer, and there’s even a DAC onboard for connecting directly with computers over USB.

At , it sits perfectly in-between its siblings — the HD3 and HD6. For its size and price-point, the HD4 completes Audioengine's award-winning HD series. We think it offers the perfect upgrade for a desktop, turntable, or main living room system where space is limited but performance cannot be compromised. We can’t wait to tell you more about its performance as a tabletop system and as a work from home setup.

Packaging, Design & Build Quality

In the box, three microfiber bags cover and protect everything. All the included cables are found in the smaller microfiber bag which includes everything needed to get up and running to hear music quickly. In the package, a pair of left and right banana connectors, a pair of left and right RCA cables, and a 3.5mm stereo mini-plug for connecting with a laptop or turntable’s built-in phono stage are included. If you want to take advantage of the HD4’s built-in DAC, you’ll need to source your own with the correct USB connections for use with your computer.

The HD4 comes in two color options. Our test unit arrived in a natural walnut MDF cabinet with a wood-veneer, but a more modern-looking black is also available. When we removed them from the microfiber protective bags, we noticed their simple but cool "old-school" look. The walnut features a minimalistic design with rounded corners that will add a touch of retro-flavored "warmth" to the style & decor of just about any room.

As usual with Audioengine products, the build quality is immediately evident. Similar to the more expensive HD6, the HD4 wireless is constructed with components that are custom designed in-house at the company’s Austin, Texas facility, and the MDF wood-veneer cabinets feel sturdy, and well-braced. The right speaker houses the amplifier, so it weighs 7 ½ pounds and the left speaker weighs about 5 ½ pounds.

What sets the new Audioengine HD4 apart from both the HD3 and HD6 is the size and price. Dimensionally, the HD4’s MDF cabinet stands right in-between its two siblings, standing 9-inches tall, 5 ½-inches wide and 6 ½-inches deep. This is substantially smaller than its bigger brother — HD6.

For comparison with the other speakers in the HD series, the HD3 is 3-inches shorter than the HD4, and 4 ¼-inches wide by 5 ½-inches deep. The bigger brother, HD6, is the largest in the series and stands 11 ¾-inches tall, about 7-inches wide, and 10-inches deep. Similar to the other speakers in the HD series, horizontal venting ports on the lower facades of both speaker cabinets are carved into the finished wood-veneer right below a brushed metal plate, which also features a cool engraving of the Audioengine logo.

A black grille magnetically attaches to the front of the speaker cabinet just above the brushed metal plate. When you remove the grill, the HD4 has a professional studio monitor-look for a view of the woofer and the tweeter. The speaker consists of a 4-inch Aramid fiber woofer complemented with a ¾-inch silk dome tweeter. The built-in analog Dual Class AB monolithic power amps are housed inside serious retro-looking MDF cabinets with a wood veneer that are precisely tuned.

We like the studio monitor look of the new HD4 without the grill. Removing it gives the HD4 a more modern reboot to the HD4’s unapologetically evocative vibe. With a turntable or a computer positioned between a pair of HD4 Wireless Powered speakers, you will have a professional-looking studio monitor setup and modern functionality that’s ready to take on the digital world. As an all-in-one bookshelf speaker setup, we think the new Audioengine HD4 powered speakers are a great solution for anyone who has restricted space but still wants the better performance of a larger compact speaker.

The right speaker houses the amplifier, volume control, and input and output connections. On the front panel, there’s a volume control knob, a push-button switch to toggle the aptX Bluetooth pairing mode on or off, and a 3.5mm mini-plug input that lets you connect a pair of headphones at your desk.

The rest of the connections are available from the rear panel. From the rear, there's another 3.5mm stereo mini-plug input to connect to a laptop, smartphone, or portable music player, a set of left/right RCA inputs for connecting a phono preamp and a turntable, a micro USB input, a Bluetooth antenna and on/off power switch. There’s also a set of RCA audio outputs for connecting to a subwoofer. Once you get the right speaker all connected, you simply run the banana cables to the left speaker, plug in the included power supply, and connect your audio source via Bluetooth, USB, stereo mini-plug, or RCA and you’re in business.

Features & Technology

The HD4 is an active speaker which gives it a host of audio advantages when it comes to performance. In a normal stereo system, you have speakers and an amplifier to power the speakers. The amplifier is actually composed of two parts, a preamp, and a power amplifier. The preamp does all the switching and volume control, while the power amp drives the speakers. Your speakers then have two or more speaker components that handle the different frequencies. Inside the speaker is what is called a "crossover." This directs the correct frequencies to the different speaker drivers.

This is how 95% of stereo systems are done these days, but there are some disadvantages to this design. First, the company making the amplifier has no idea what kind of speakers it will be connected to, so they have to optimize its performance for a wide range of speaker characteristics. The speakers will use what is called a "passive crossover" that basically chokes off the signals that should not go to the different speaker drivers. Some dynamics and efficiency are lost by doing it this way.

Active speakers are quite a bit different as they are designed to work as a complete system. Active speakers have a separate amplifier for each speaker driver and use an electronic crossover rather than a passive crossover.

In a passive design, the crossover is after the power amplifier and inside the speaker. With an active design, it happens before the signal gets to the power amp, meaning there is zero loss in dynamics or efficiency. The engineer designing the power amp knows exactly what the speaker load will be, so the amp is perfectly mated to the speaker driver.

This type of system results in a much more open, dynamic, and effortless sound when done properly.

Most manufacturers use digital amplifiers to keep their costs down — but Audioengine uses analog Dual Class AB monolithic power amps here, and these are tuned just right for each speaker in the series. Analog amps will typically have a warmer sound profile and give your music a more tuneful sense-of-timing and better rhythm-and-pacing, overall.

We think the use of analog amps is a true testament to Audioengine’s dedication to inspiring more people to enjoy music with better sound. The use of analog components here is a nice touch at this price-point, and we think it’s a big part of what made listening to music with these so enjoyable.

Similar to the HD3 and the HD6, the new HD4 has Audioengine’s best selling DAC built into it — the Audioengine D1 24-bit headphone DAC/Amp. It also sports the latest and greatest Bluetooth 5.0 specification. This extends the wireless operating range with compatible Bluetooth devices to 100ft! And, as usual, Audioengine didn’t stop here when it built a wireless speaker packing the latest Bluetooth iteration. Audioengine uses Qualcomm’s aptX and aptX HD Bluetooth tech in the HD4 for CD-like audio quality — think music that’s more detailed with tighter bass and clearer mid-range.

Performance

Audioengine’s HD series has been a big hit with our customers here at Audio Advice. We find that most people use bookshelf or desktop speakers with computer setups. However, since the HD series was released alongside the revival of vinyl, we’ve noticed a lot more people using Audioengine bookshelf speakers to play music with turntables too.

When testing the HD4, we allowed it to break in first with a 3.5mm stereo mini-plug connected to a laptop streaming Qobuz. We stationed the HD4 powered bookshelf speakers on a computer desk and tested them as a near-field setup with a direct USB connection. As usual with Audioengine speakers, we were impressed with the HD4’s stereo imaging. Next, we tested the speakers in an open room setting with a vinyl record player using the RCA connection to a phono preamp and as a wireless speaker system streaming aptX HD.

To get the best results on your work desk, you’ll want to form an equilateral triangle with the speakers equally spaced apart so that you’re also sitting at an equal distance from the speakers. Play around with the angle of the speakers until the vocals sound like they are in the middle. Audioengine desktop stands will stabilize the position you set and they will improve the sound of the bass as well. The stereo image really came alive and shined as a near-field monitor on our work desk when we plugged the USB output from our laptop into the HD4 and played a modern recording by the electro-pop duo Chromeo. Recorded in 2020 while under lockdown for a light-hearted EP titled “Quarantine Casanova,” the song “Clorox Wipe” balances a nostalgic attitude with modern recording techniques. Featuring cool vintage synths, retro talkbox effects, disco basslines, and plucky guitars, the HD4 highlighted all of these instruments in the stereo field with warmth and clarity. We really enjoyed listening to the fresh new take on a vintage vibe while working in front of the HD4 powered speakers. The tuneful sense of timing made working from home feel fun and energizing. Audioengine speakers generally do a great job of warming up the sound — that’s most likely because of the analog amps inside. Overall, the rhythm and pacing of the sound coming out of the HD4 inspired us to tap our feet along with the music. As bookshelf speakers, there’s no argument these are designed to sound best when listening up close. However, the HD4 performed better than we anticipated as a tabletop setup In our living room space. We used the U-Turn Audio Orbit Plus Turntable which is a great turntable for the money. It has a phono stage built-in, and we used this to play back a vinyl pressing of “Warrior” — recorded in 1984 by the classic rock outfit, Scandal. This recording features overdubbed rock guitars, edgy lead vocals from Patty Smyth, and a big studio budget. It’s the quintessential “arena rock” sound that uses analog recording techniques characteristic of that era. The rhythm and pacing of the bass guitar came alive with a tuneful sense of timing that made us tap our feet along with the music while preparing food in the kitchen. When we cranked up the volume to 75%, we were hearing a room-filling sound that made us want to sing along with this mega-anthem. We even belted out the chorus as though we were attending a live concert! Overall, the HD4’s pack a warm musical punch in an open room that’s easy to get lost in. The user-friendliness of Audioengine’s design really came alive when we switched our audio source from vinyl to streaming Qobuz over Bluetooth without having to touch anything on the speaker. This allowed us to continue our open-room session from our couch without interrupting the mood. First, we streamed high-quality audio with Qobuz from an iPhone to the HD4 over regular Bluetooth. The sound was warm but clean, overall. The mids and highs were distinct and clear, and the soundstage filled our living room space. The volume of the presentation was more than suitable for cooking or enjoying an activity with music playing in the background. We noticed the presentation was also room-filling enough to entertain guests or host a dance party. We wanted to test the sound of the aptX HD, so we streamed Qobuz using a Google Pixel 3a directly to the HD4. This is where the clarity of details in the music became a lot more apparent and a little closer to the sound of vinyl. The separation of details in the stereo image opened up wider with dynamics in the music we couldn’t hear previously. This was especially noticeable during a remastered version of Peter Gabriel’s smash hit “Sledgehammer.” Recorded in 1985 as the lead single for Peter Gabriel’s fifth studio album “So,” the song features a powerful rhythm section. We could hear the kick drum and the "crack" of the snare landing musically in the center of the HD4’s stereo image. When we spread the speakers a little further apart, the kick and snare drums retained their focal points in the center of the mix distinctly with a warm and musical tone. This helped create more depth and improved the separation of details coming out. Turning the volume knob past 50% presented a stereo field with enough volume to fill our living room with good sounding music and make us tap our feet to the beat. Overall, aptX HD presented good quality sound in an open-room scenario that exceeded our expectations for such a small compact speaker system. Having a greater range with Bluetooth 5.0 to roam around the house freely was a subtle plus. Still having playback controls with our phones from the couch or another room without interruptions was also very handy.

Overall Recommendation

The HD4 was designed for anyone looking for a powered bookshelf system with upgraded analog amps and the convenience of USB and aptX HD. It sits right in between the HD3 and the HD6 in terms of size and price.

If the HD3 is a little too small for your needs, and the HD6 is either too big or more than you're looking to spend, then strongly consider the HD4. At for the pair, we think the HD4 powered bookshelf speaker system is that perfect balance that sits right in-between for the perfect size and price-point.

If you like the Audioengine sound and need a larger desktop speaker system with even more output, then step things up to the HD6. For less than $300 more, you will get even more inputs and outputs with bigger sound suitable for larger living spaces.

Adding a subwoofer to the HD4 will present more bottom-end weight. We recommend the Audioengine S8 subwoofer because it’s an excellent addition to this system that will add more immersion for bass-heavy songs.

Even without a subwoofer, the HD4 will still present good low-end that will complement any living room system using a TV, turntable, phone, or tablet as a source. However, if you have a larger room and budget, and you want deeper bass, the HD6 is the best option. With multiple inputs, it will integrate with almost any setup since you don’t have to choose just one source. Listen to vinyl with the RCA connections, Bluetooth your favorite streaming service without touching anything on the speaker, or enjoy the studio-quality stereo image from your desk with USB or the headphone jack.

Anyone who appreciates high performance at a great value will appreciate the amount of flexibility and the sound quality it gives you.

At these price-points, Audioengine speakers are great for entertaining guests with a warm sound. The studio-quality stereo image of the HD4 will shine as a near-field monitor on your work desk, but it will fill up an open room with great sound too. For anyone who wants to revive an old vinyl record collection with the modern conveniences of Bluetooth 5.0 and the quality of aptX HD, who wouldn’t choose this powerful all-in-one bookshelf system for a tabletop or a desk?