To Be Determined

    AudioEngine’s New S6 Subwoofer with the HD4 Home Music System

    Issue 157

    In Copper Issue 149 I talked about how my personal circumstances could soon be changing fairly dramatically in about a year and a half (you can read about that here). It’s still unclear which direction we’ll eventually head, but it now appears it won’t be Providence, Rhode Island. It’s looking more like Charleston, South Carolina, which is still a nice coastal town, but without all that snow! And I have a long history with Charleston; I helped a high school friend and his dad rehab a 35-foot sailboat there between my freshman and sophomore years of college, and my wife and I were later married there. I’ve vacationed there many times over a 35-plus-year period.  There’s a lot to love about the Low Country.

    The one thing that hasn’t changed is that I could potentially be downsizing my home stereo system significantly. And I’ve therefore been spending a fair amount of time recently listening to a much smaller, seriously less-expensive system that still (at this point, at least) includes the $449 AudioEngine HD4 Home Music System. If you read my previous piece, you’ll probably remember that the one area I felt the HD4 powered loudspeaker system was lacking in was satisfyingly deep bass; you just couldn’t push them hard enough to get believable bass from their four-inch aramid fiber woofers. The 60 watt per channel (peak power) Class AB internal amps provided plenty of juice to get a very nice midrange and treble presentation, but just didn’t have enough oomph to get those woofers cranking, pretty much under any setup situation I tried. Remember, though, I did much of my listening in a fairly massive 26 by 30-foot living/dining/kitchen area with a 14-foot vaulted ceiling. Which is a challenging environment for a pair of powered loudspeakers with only four-inch woofers – no wonder the bass was a tad underwhelming!


    Locating the S6 close to the HD4 speakers was ideal for making the audio connections, but also proved to be the correct location acoustically.

    Locating the S6 close to the HD4 speakers was ideal for making the audio connections, but also proved to be the correct location acoustically.


    Taking them down to my main listening room where they were paired with my REL subwoofer helped a lot, but to be honest, the REL wasn’t a particularly good match with the HD4 speakers. I thought about reaching out to AudioEngine to get one of their powered subs for review, but the only model in their product lineup had been out for several years already, so I resisted that temptation. I fully realized that I’d probably end up just buying one to help confirm that the HD4 was actually going to be fully appropriate for my needs – even my already significantly scaled-back needs. Then two weeks ago, I received an email from Brady at AudioEngine; they had a new powered subwoofer that was now available for review, the S6. Was I interested? You bet – let the rejoicing begin!


    The matte gray finish and black grill helps the S6 blend in well in my room.

    The matte gray finish and black grill helps the S6 blend in well in my room.


    AudioEngine S6 Powered Subwoofer

    The S6 is AudioEngine’s smallest sub, with a custom designed 6-inch aramid fiber, long-throw, front-firing woofer. The tuned, sealed-box subwoofer cabinet is made from 15mm thick heavily-braced MDF, and measures 10 x 8.7 x 10 inches – it’s relatively compact as powered subs go, and can be placed unobtrusively just about anywhere. The sub weighs about 15.5 lbs., but its substantial heft surprised me when I picked up the shipping box on my front porch – I would have guessed it was much heavier. The sealed enclosure is tuned to match the woofer, and all internal elements of the amp are custom-designed in the goal of maximum sonic performance. The S6 features an attractive dark gray satin finish and has a detachable black fabric grill that covers the entire front-facing panel. Although it’s virtually invisible in its current surroundings, its styling perfectly fits the mid-century modern aesthetic of my home (translation: my wife doesn’t find it too objectionable).

    AudioEngine S6, no grille.


    The S6 features a Class D internal amplifier that outputs 140 watts RMS (210 watts of peak power), and has a frequency response of 33 Hz to 132 Hz, ± 1.5 dB. The unit features an A-weighted signal-to-noise rating of 100dB (pretty surprising for a 6-inch woofer!), and the internal amp has circuitry to limit current, temperature extremes, and buffer on/off power transient noise. The S6 features the standard range of line-level inputs and controls for phase (0/180 degrees), crossover frequency (40 – 130 Hz, continuously variable), and also offers a standby switch, which enables the unit to power on when it senses a signal input. It’s a very handy feature, which allows you to pretty much place the S6 out of sight and out of mind without having to worry about turning it on and off with each use. Its standby power consumption is less than 1 watt, which is way less than a typical LED light bulb.


    The rear panel offers most of the controls typically found on full-size units.

    The rear panel offers most of the controls typically found on full-size units.


    All cables necessary for connection to the HD 4 speakers are included in the package, which includes a two-meter RCA cable (my preferred connection method) as well as a two-meter stereo cable with 3.5 mm jacks at each end. Either cable is plenty long to connect to the rear panel of the left HD4 unit, and I have the S6 positioned on the floor between that speaker and the room’s side wall. In typical AudioEngine style, the subwoofer comes enclosed in a nice microfiber bag, with an additional one that contains all the necessary cables. It’s a really nice touch that elevates AudioEngine’s product offerings a bit above the norm.

    As with everything else in the house, it's a constant battle with plants and stands to get any equipment where you want it!

    As with everything else in the house, it’s a constant battle with plants and stands to get any equipment where you want it!


    Use and Listening Tests

    The S6 was a snap to set up and get going, and it actually took probably less than an hour for me to arrive at a bass level and balance that I felt significantly enhanced the performance of the HD4 loudspeakers. I ended up placing the S6 in one of my room’s corners; this was mainly to allow convenient access to the HD4’s output connectors. Yeah, yeah, I know all about the conventional wisdom of not placing a subwoofer in a corner, but that setup works like a charm with my REL sub. And this is a really large room, so any bass reinforcement for the sub provided by corner placement could only be a good thing as far as I was concerned. As is usual with my subwoofer setup experiences, early on I was a bit overenthusiastic and set the level a bit too high. I eventually ended up going back and forth several times and reducing the sub level to a point that I felt offered a better balance with a variety of music. I started out with the crossover frequency set much higher, but as my experimentation went along, I found that the best overall blend with the HD4 was with the crossover set to 40 Hz. I mostly used my Moto G5S cell phone’s Qobuz client for listening via the HD4’s Bluetooth connection. But I also used a pigtail connector to attach an AudioQuest Cobalt DAC to the Moto G5S with a wired connection to the 3.5 mm input on the HD4’s rear panel. The latter setup provided better overall sound; the AudioQuest Cobalt DAC is easily much better-sounding than either the HD4’s internal DAC, or with a straight connection to my Moto G5S.

    The AudioQuest DragonFly Cobalt helped provide superb (and often high-res) sound to the HD4/S6 combo.

    The AudioQuest DragonFly Cobalt helped provide superb (and often high-res) sound to the HD4/S6 combo.


    For initial listening and setup, I chose several old favorites from jazz pianist Cyrus Chestnut, whose albums uniformly seem to have very deep and well-recorded bass. That proved very useful to get a good baseline for adjusting the S6’s output to the room and to match the output to the HD4 speakers. For the remainder of my listening, I chose selections from Qobuz’s new releases section, including new indie rock from Alt-J’s The Dream, South Korean jazz singer Youn Sun Nah’s Waking World, alternative chanteuse Cat Power’s Covers, and Russian pianist Daniil Trifonov’s new album Bach: The Art of Life. Alt-J has kind of a mid-seventies, Pink Floyd-ish kind of vibe (without all the Roger Waters acerbic angst), and all the tunes feature very deep bass. With this music, the HD4 speakers, which had previously seemed pretty underpowered in this large room, now seemed quite capable, with the added bass from the S6 giving them the much needed lower-octave oomph to make them seem perfectly at home.

    The same was true of Cat Power’s Covers, which is unsurprisingly an album of cover tunes; Chan Marshall’s voice is quite evocative on her delivery of the opening track, Frank Ocean’s “Bad Religion.” Marshall’s vocal range mostly resides in the lower registers, and the HD4’s presentation of this track was absolutely night-and-day different when the S6 was switched out of the loop. The track became instantly more pedestrian-sounding without the S6, but regained its power and was more engaging with the S6 added to the mix. Waking World from jazz chanteuse Youn Sun Nah has been getting a lot of traction recently – but is it really jazz? Regardless, her stark and beautiful vocal on the opening track, “Bird On The Ground,” was punctuated with a deep and effective running electric bass line that made the track more powerful with the S6 added to the mix. And while Daniil Trifonov’s solo piano doesn’t focus on the deepest octaves of the piano’s range, the recording gained a significant level of power and presence with the S6 attached to the HD4 speakers. It just sounded more like an actual piano was in the room with the S6 than without.



    In my previous review, I mentioned more than once that the AudioEngine HD4 was a great-sounding loudspeaker system, but was underpowered and lacking in low bass when compared to their flagship HD6 powered speakers. The HD6 offers more than double the output power of the HD4, and their larger cabinets and more propulsive 6-inch woofers brings them much closer to my personal ideal of what the performance baseline should be for loudspeakers that I’m going to want to be happy with forever. The HD6 is definitely that loudspeaker – it’s as close to a forever loudspeaker as I’ve ever heard in this category. The HD6 is priced at $250 more in overall MSRP than the $449 HD4 – but when you add to that the extra $299 for the S6, that takes the HD4/S6 package price beyond that of the HD6.

    That makes this a very tough call for me; I like what the extra power provided by the HD6 adds to the big picture in the overall sound of the loudspeaker. And the HD6 will play with more realism and with a scale that the HD4 alone can’t touch. But when you add the 210 total watts brought by the S6 to the equation, even though it only employs a 6-inch woofer, the long-throw bass performance from the S6 is indeed impressive. So it boils down to what do I really want – great bass and acceptably great performance from the S6/HD4 combo, or more impressive overall performance with less bass from the HD6? The HD6 has the same complement of inputs as the HD4; so adding an S6 to the HD6 would make a compelling system that’s priced just south of $1K, which is still very inexpensive in comparison to my current system. And would offer an impressive level of performance across the frequency spectrum.

    But hey, it’s always great to have choices, right? Regardless, the AudioEngine S6, whether in a solely AudioEngine system or augmenting any other powered loudspeakers, comes very highly recommended.

    AudioEngine HD4 Powered Loudspeakers: $449.00 MSRP, S6 Powered Subwoofer: $299.00 MSRP,

    All images courtesy of AudioEngine and the author

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