It’s no secret that we are fans of KRK monitor speakers, and we use them in at least three of our studios. We first reviewed KRK subwoofers a few years back and a few revisions ago. But KRK has refreshed their line of subs, so it was time to see and hear what’s new.

Category Value Rating
Features 20%
Usability 25%
Sound 25%
Documentation & Support 10%
Price 20%
3.6 stars or better: Outstanding, WIHO Award

3 stars or better: Worth considering
2 stars or better: Suited to specific needs
1 star or less: Not recommended


Available in a range of sizes, we looked at the S10.4, which features a 10” glass aramid composite woofer in KRK’s familiar yellow coloring. The cabinet is a reinforced MDF enclosure with a redesigned front port. The frequency response is 30Hz—110Hz, with a maximum SPL of 117.2 dB from a 160W class D power amplifier. As a nice touch, if you intend to place the subwoofer on a hard floor, an EVA foam isolation pad is included. Just peel off the backing and it affixes to the speaker cabinet.

Inputs and outputs are on balanced XLR and unbalanced quarter-inch jacks, as well as a set of unbalanced RCA connections, and the rear panel provides direct access to a variety of features.

There are four selectable crossover points: 60Hz, 70Hz, 80Hz, and 90Hz, as well as a switch to flip the speaker’s polarity. The S10.4 goes into a low-powered sleep mode automatically after not receiving any audio signals for thirty minutes, but there is a switch to bypass the sleep mode if you require always-on operation.

A quarter-inch jack provides for connecting a momentary/latching footswitch in order to bypass the sub and send the full-range signal to your main speakers. We used a BOSS FS-5L without any issues.


Use of the S10.4 was extremely straightforward once we sorted out the right set of cables. However, one gripe we had with the second-generation subwoofer remains in this fourth generation: unlike most KRK monitor speakers, the KRK logo on the front of the subwoofer does not illuminate when the speaker is turned On.

There is a power indicator light on the rear panel, but considering that all of our other KRK speakers have illuminated logos that switch to a dim pulse when in standby mode, we found it somewhat frustrating to glance at the sub and wonder if it was On or Off. At least our footswitch had an LED to indicate if the sub was bypassed or not, but if you’re working without a battery-powered footswitch as we did in some of our setups, you may find yourself reaching down to touch the edge of the woofer with your hand to confirm its operation.

While previous generation KRK subs had a metal grille to protect the speaker, the S10.4 speaker is exposed by default, which can be an issue if you’re placing the sub beneath your mix desk and within accidental kicking range of your foot. Fortunately, KRK informed us that they have optional grills in production that should be available for purchase this Fall 2021.


We tested the KRK S10.4 subwoofer in both a mix studio setting as well as in a keyboard rig for personal monitoring. We paired the sub with KRK’s fourth-generation V8 and V4 monitor speakers.

The S10.4 is a very quiet sub to be sure, but whether it will add value to your setup is dependent upon a number of factors including the style of music you produce/mix and the size/range of your nearfield monitor speakers. If you’re doing surround mixing for film/television, you absolutely need a sub. Mixing some rap and hip-hop? You probably want a sub as well for all that sub-bass stuff you need to keep the windows rattling. Mixing pop, rock, prog, metal, alternative? We’ll consider adding a sub purely optional based on how good your nearfield speakers are to begin with.

When we paired the S10.4 with our KRK fourth-generation V8 speakers, which have an eight-inch woofer and a frequency response that goes down to an impressive 35Hz, the additional low frequency coverage was minimal at best, and to be frank, made our low end a bit cloudy and harder to mix, regardless of which crossover point we set.

If you have the V8 speakers or other, larger nearfields with an already extended low-end coverage, you’ll want to step up to the larger KRK S12.4 sub, which covers frequencies down to 26Hz. There’s just not enough low frequency coverage gained from this ten-inch sub to make a difference. This is less a ding on the sub than it is praise for the V8 speakers, which already do a remarkable job with their low-frequency coverage.

With our V4 speakers, which as you may surmise feature four-inch woofers (and a frequency response down to only 58Hz), the addition of the S10.4 was a blessing! If you’re mixing on smaller speakers, the addition of this sub makes a drastic improvement to your monitoring, and we wouldn’t hesitate to demand it.

We relocated the V4/S10.4 setup from our secondary mix desk to the keyboard rig in our studio, and it made monitoring at the keyboards a heavenly sounding experience, with low piano notes and orchestral sounds delivering depth we could feel as well as hear. Bottom line for us: we’re buying this sub if only to keep it in the studio keyboard rig.

Whether or not you need a sub for mixing isn’t always an easy answer, but if you have smaller nearfield speakers, adding the S10.4 will be a welcome improvement. If your speakers are in the 6-8” range and have lower-frequency coverage than you can get from smaller nearfield options, you will need to step up to the KRK S12.4 subwoofer, as the ten-inch model just won’t make a significant difference.

Documentation and Product Support

Documentation for the S10.4 speakers is minimal but thorough.

KRK speakers include a 3-year warranty from the original date of purchase. We can affirm that customer service is excellent as over the years, we have blown a speaker or two and received fabulous support (and replacement parts).


The KRK S10.4 subwoofer (MSRP $549) sells for approximately $450, which is a good price for this well spec’ed speaker. If you need the larger S12.4, however, the price jumps significantly to $800 street.

The optional grills have an MSRP of just $29.99 and $34.99 respectively.

We have to reiterate, though, that if you already have big nearfield speakers with good low-frequency coverage, you will not benefit by cost-saving with the smaller sub. The larger S12.4 has a more powerful amplifier and a significant low-end bass extension compared with the S10.4.

If you just need an extremely compact solution, KRK also makes a smaller S8.4 subwoofer (with optional grill as well).

Contact Information

KRK Systems