Short answer: the JBL M2 Master Reference Monitor. It ranks #1 of 31 powered bookshelf speakers by sound quality; the Genelec 8351B ranks #6.
What the JBL M2 Master Reference Monitor offers: Flagship quasi-active two-way with a 15-inch 2216Nd woofer and D2 compression driver crossing near 800Hz through a large Image Control Waveguide. Watch for: The required bi-amplification/DSP ecosystem is expensive and complex; Erin’s Crown I-Tech 5000HD had fans loud enough that he moved it to another room for measurements.
What the Genelec 8351B offers: CEA2034 spinorama shows exceptionally flat response both on- and off-axis. Watch for: Deep bass distortion rises substantially at higher output (96dB SPL/1m) - the reviewer notes “deep bass suffers” below about 100Hz.
Buy the JBL M2 Master Reference Monitor if sound quality matters more than the price. Buy the Genelec 8351B if the price matters more than sound quality.
Specifications Side By Side
| JBL M2 Master Reference Monitor | Genelec 8351B | |
|---|---|---|
| Price | Contact dealer | $9150 |
| Ranked | #1 of 31 in Large Size Powered Bookshelf Speakers | #6 of 31 in Large Size Powered Bookshelf Speakers |
| Bass Extension (-3dB) | 34Hz (measured, Erin’s Audio Corner) | 33Hz (measured, Audio Science Review) |
| Sensitivity | Not applicable (externally bi-amplified DSP system) | - |
| Drivers | 15" 2216Nd woofer; D2 compression driver in Image Control Waveguide | 8.6" woofer, 5" coaxial with tweeter midrange, 0.75" (19mm) coaxial tweeter |
| Crossover | 800Hz active DSP | - |
| Max SPL | 123dB manufacturer specified | 113dB @ 1m |
| Weight | 130 lb each | 31.1 lbs / 14.1 kg each |
| Amplification | External two-channel amplification and JBL DSP tuning required | - |
| Bass Extension (-10dB) | - | 28Hz (measured, Audio Science Review) |
| Dimensions | - | 17"H x 11.3"W x 10.9"D (431.8 x 287 x 276.9 mm) |
| Inputs | - | XLR |
| App | - | Yes (GLM) |
| Bluetooth | - | No |
| DSP | - | Yes |
| EQ | - | Yes (via GLM software) |
| Frequency Response | - | 32Hz - 40kHz (±1.5dB) (Manufacturer specified) |
| Output Power | - | 550w Per Speaker |
Related Speaker Comparisons
More useful head-to-heads from the same speaker class:
- Kii THREE vs Buchardt A10
- Kii THREE vs Buchardt A500
- Kii THREE vs JBL 4329P
- Genelec 8351B vs SHIVAUDYO Point Zero
- Genelec 8351B vs Neumann KH420
The Two Speakers In Full
JBL M2 Master Reference Monitor: Contact dealer JBL Professional Dealer Locator
Pros: Flagship quasi-active two-way with a 15-inch 2216Nd woofer and D2 compression driver crossing near 800Hz through a large Image Control Waveguide. Erin measured F3 at 34Hz, less than 1% THD at 86 and 96dB, and only about 0.25dB compression by 102dB. Radiation stays broadly constant to roughly +/-60 degrees through 8-9kHz, producing excellent direct/reflected-sound agreement and enormous clean dynamic range. External DSP amplification permits precise factory crossover, phase and response correction.
Cons: The required bi-amplification/DSP ecosystem is expensive and complex; Erin’s Crown I-Tech 5000HD had fans loud enough that he moved it to another room for measurements. Midrange resonances remain visible despite the otherwise neutral response, and treble dispersion narrows above roughly 9kHz before beaming above 12kHz. Each 130-pound enclosure is physically imposing. This is an amplified system, so passive impedance and sensitivity figures are not applicable to the complete configured product.
Full JBL M2 Master Reference Monitor review and specifications →
| Amplification | External two-channel amplification and JBL DSP tuning required |
|---|---|
| Bass Extension (-3dB) | 34Hz (measured, Erin's Audio Corner) |
| Crossover | 800Hz active DSP |
| Drivers | 15" 2216Nd woofer; D2 compression driver in Image Control Waveguide |
| Max SPL | 123dB manufacturer specified |
| Sensitivity | Not applicable (externally bi-amplified DSP system) |
| Weight | 130 lb each |
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Genelec 8351B: $9150 Bhphotovideo
Pros: CEA2034 spinorama shows exceptionally flat response both on- and off-axis. Predicted in-room response is “as good as it gets” - should sound very neutral in nearly any room. Horizontal beamwidth of about ±50 degrees is described by the reviewer as exceptionally smooth, a model example of well-executed directivity control. Vertical directivity is nearly as good as horizontal, a benefit of its coaxial driver design that’s rare among non-coaxial monitors. Distortion at 86dB SPL/1m is remarkably low - the reviewer says it’s “better than many headphones.”
Cons: Deep bass distortion rises substantially at higher output (96dB SPL/1m) - the reviewer notes “deep bass suffers” below about 100Hz. A distortion spike also appears near 8-10kHz at that same higher output level. Cumulative spectral decay (waterfall) measurements show resonances around 1-2kHz. Very expensive.
Full Genelec 8351B review and specifications →
| App | Yes (GLM) |
|---|---|
| Bass Extension (-10dB) | 28Hz (measured, Audio Science Review) |
| Bass Extension (-3dB) | 33Hz (measured, Audio Science Review) |
| Bluetooth | No |
| DSP | Yes |
| Dimensions | 17"H x 11.3"W x 10.9"D (431.8 x 287 x 276.9 mm) |
| Drivers | 8.6" woofer, 5" coaxial with tweeter midrange, 0.75" (19mm) coaxial tweeter |
| EQ | Yes (via GLM software) |
| Frequency Response | 32Hz - 40kHz (±1.5dB) (Manufacturer specified) |
| Inputs | XLR |
| Max SPL | 113dB @ 1m |
| Output Power | 550w Per Speaker |
| Weight | 31.1 lbs / 14.1 kg each |
As an eBay Partner, we may be compensated if you make a purchase.
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons