JBL K2 S9900 Floorstanding Loudspeakers Review

Posted on 27th April, 2022

JBL K2 S9900 Floorstanding Loudspeakers Review

Craig Joyce experiences this mighty, US-made behemoth of a floorstander…


K2 S9900 Loudspeakers

AUD $79,999 RRP (Rosewood Finish)

Over the past few decades, the trend in floorstanding loudspeakers has been for narrower, taller speakers with a multitude of smaller mid/bass drivers, perhaps topped off by an exotic tweeter. Yet there are still some manufacturers out there doing something quite different. JBL has a long heritage in speaker design, but these days tends to be better known for consumer electronics. However, under the design tutelage of Greg Timbers (who has since moved on from JBL), the company has continually challenged preconceived ideas, producing highly accurate speakers capable of large dynamic shifts, high sound pressure levels and ruler-flat frequency response.

The K2 S9900 that you see here draws from this heritage. It is a predictably large, wide yet surprisingly shallow 3-way design, incorporating many of the features from the flagship Everest speakers. It packs a 15” low-frequency driver, a 4” compression driver and a 1” beryllium super tweeter compression driver. JBL actually calls it an augmented 2-way design, as the S9900 uses a single midrange crossover at 900Hz to blend a single woofer to the compression driver and horn combination. An ultra-high frequency driver is brought in at 15kHz to cover two octaves of ultrasonic frequencies. Above 700Hz, the high-frequency compression driver and horn combination operate unassisted beyond 22kHz. 

This makes for a claimed frequency response of 48Hz to 50kHz, ±6 dB. The S9900’s other specs are impressive too. It’s said to have 500W power handling, with an easy-going 8-ohm nominal impedance that only drops to 7 ohms around 100Hz, and 93dB sensitivity. This makes the speaker a dreamboat for tube amplifiers and lower power Class A solid-state designs. The speakers can be bi-amplified and contain separate high and low-frequency crossover networks, by the way. 

The S9900 has a large 100mm diameter flared rear port with a tuning frequency of 34Hz, alongside the input connections on a massive diecast aluminium plate. In addition to input binding posts, this rear plate includes rotary switches that allow for the selection of bi-amplification, presence adjustment – which raises or lowers the drive by approximately 0.5dB in the range of 1.5 to 3kHz – and high-frequency level trim which attenuates by approximately 0.5dB from 1kHz to about 20kHz. A removable cover provides access to the 9-volt battery used for capacitor bias. 


Arriving on a pallet and more akin to a small fridge in size, these 1.2 metre tall, 560mm wide loudspeakers top out on the scales at circa 85kg per side. Positioning them for optimal room response is definitely not a one-person job. The relatively shallow shape may pose challenges for some narrow rooms but creates opportunities for locating them closer to a wall than other speakers might permit. The entire speaker enclosures rest on four stainless steel foot assemblies, with stainless steel coasters provided to protect wood and tile floors from the risk of damage from the spiked feet. If you want to put isolation feet on them, you will need a M12 thread.

The finish is nothing short of magnificent. A proprietary process is used to interlock a 25mm thick MDF enclosure which decouples multiple layers of curved MDF with voids filled by a foam after forming, resulting in excellent fit and finish. The factory finish is rosewood, but for an additional cost, you can elect to finish the speakers in a selection of six automotive grade finishes including British Racing Green Metallic, Ferrari Red and Polar White.

For this review, I paired the S9900s with McIntosh MC1201 monobloc power amplifiers, a Classe CP800v2 preamplifier and an MSB Premier DAC – with Qobuz over Roon providing high-resolution source material.


The K2 S9900 maintains the tradition of big JBLs by delivering a vast, fast and powerful sound. At the same time, there is precious little of the colouration heard in traditional, old school speakers from this marque – this one sounds thoroughly modern with fine detail retrieval and impressive sound staging. 

When you have a speaker with 15” bass drivers, you expect it to have a serious bass – but whether or not it’s properly controlled is another matter. The K2 S9900 impressed hugely on both these counts. The Pale Moth by Plaid blew me away, the JBL showing great transient speed and power in the low frequencies. Also, acoustic guitar work seamlessly punctuated the mix, and some very complex segments were rendered cleanly and without confusion; this let the music shine. 

Soundstaging is seriously impressive, too. One of my favourite tracks to test speaker imaging is Japanese Roots by Také Daké & Neptune. The K2 S9900 didn’t disappoint here, as the bamboo instruments appeared in a holographic image before me, each one clearly articulated in a very specific point in three-dimensional space. This was despite the relative complexity of the music, which makes lesser loudspeakers break out into a sweat.

Another great facet of the K2 S9900 is its tonal accuracy; this speaker just sounds natural, unprocessed and believable. With sparse programme material like the Johnny Cash cover of I Won’t Back Down, the music almost became a religious experience in my listening room. Guitars sparkled and shone, and vocals were accurately rendered and true to life – indeed, Cash’s voice really drew me in. This track was very well produced by Rick Rubin, and has a sense of immediacy that’s almost palpable – something I’ve never heard before in my system.

Andy Partridge from XTC has created one of the best-produced libraries of pop music, and The Smartest Monkeys is a great reference track for rock listeners. Via the K2 S9900, from the initial electric guitar panning and Andy’s lead vocals, all I could think of is that Radiohead song title, Everything In Its Right Place. When the rest of the band comes in, and the bass and drums land ahead of the first chorus, the separation of each and every drum hit is staggering. Meanwhile, the previously hidden – to me anyway – sub-bass rounded out the audible landscape with aplomb. This loudspeaker behaves less like a hi-fi design and more like a huge studio monitor in terms of accuracy to the original recording – as well as an almost ruthless ability to unpick poorly recorded source material.

JBL’s detractors joke that its name stands for ‘Just Bloody Loud’, and in days gone by, perhaps there was a grain of truth in that. Yet nowadays, the K2 S9900 does quality as well as quantity, and this forms much of this speaker’s appeal. You can have a big box that captures every last nuance of the aforementioned XTC track, and still blow the doors off the listening room – so to speak. For example, nothing crunches a room at high volumes like meticulously produced techno. Motion The Dance by Untold is a growling, building monster that uses a minimal production approach before devolving into pretty synth passages, and then finally, distorted filtered bass leads. The JBL’s grace under pressure – when the amplifier is really turned up – is quite a thing to behold. The mid and high-frequency content at high listening levels stays smooth and couth; indeed, the speaker sounds so clean that there exists a real danger of progressive hearing loss if you’re not careful. 

Scuba is an artist well respected for dropping room compressing sub-bass levels on tracks like So You Think You’re Special. Played back at even moderate volumes, the S9900 makes this sound brutal. The representation of the opening drum hits exploded across the imaging surface. When the sub-bass arrived, the ease by which the speakers delicately reproduced the low frequencies was staggering. I knew what was happening but had never before felt the feeling in a room shift so quickly to reflect the emotional context of the source material.


While loudspeakers of this size and cost will not be to everyone’s taste or budget, there’s a whole lot of love here for JBL’s Synthesis K2 S9900. It can render complex pieces of music with accuracy and precision that borders on surgical. Yet, it can also play as loud and free of distortion as you can physically tolerate. It behaves like no other traditional loudspeaker that I have ever heard. 

The compression drivers don’t appear shouty or unnatural, which means vocals and instruments sound highly organic and true to their recordings. That massive 15” woofer continually surprises the listener with its speed and precision; you will never listen to well-produced electronica on another speaker and forget how this one so effortlessly delivers the goods. Overall then, it’s an absolutely barnstorming floorstander that you should hear if you possibly can – if you’re fortunate enough to be able to countenance buying a pair.

For more information visit JBL


    Craig Joyce's avatar

    Craig Joyce

    With an engineering degree in digital signal processing and a storied career in IT networking and cyber security, Craig loves to push the boundaries of audio technologies. An aficionado of live music with personal detours in music production and event promotion, Craig is a long time enthusiast of post punk, electronic and experimental music.

    Posted in:StereoLUX! Hi-Fi Loudspeakers Floor Standing Applause Awards 2022
    Tags: jbl  convoy 


    Want to share your opinion or get advice from other enthusiasts? Then head into the Message Forums where thousands of other enthusiasts are communicating on a daily basis.


    applause awards

    Each time StereoNET reviews a product, it is considered for an Applause Award. Winning one marks it out as a design of great quality and distinction – a special product in its class, on the grounds of either performance, value for money, or usually both.

    Applause Awards are personally issued by StereoNET’s global Editor-in-Chief, David Price – who has over three decades of experience reviewing hi-fi products at the highest level – after consulting with our senior editorial team. They are not automatically given with all reviews, nor can manufacturers purchase them.

    The StereoNET editorial team includes some of the world’s most experienced and respected hi-fi journalists with a vast wealth of knowledge. Some have edited popular English language hi-fi magazines, and others have been senior contributors to famous audio journals stretching back to the late 1970s. And we also employ professional IT and home theatre specialists who work at the cutting edge of today’s technology.

    We believe that no other online hi-fi and home cinema resource offers such expert knowledge, so when StereoNET gives an Applause Award, it is a trustworthy hallmark of quality. Receiving such an award is the prerequisite to becoming eligible for our annual Product of the Year awards, awarded only to the finest designs in their respective categories. Buyers of hi-fi, home cinema, and headphones can be sure that a StereoNET Applause Award winner is worthy of your most serious attention.