Short answer: the Genelec 8351B for better sound quality, the JBL 308P MKII for the lower price. The Genelec 8351B ranks #6 of 66 powered bookshelf speakers at $9150. The JBL 308P MKII ranks #26 at $498, $8652 cheaper.
What the JBL 308P MKII offers: CEA2034 spinorama shows an essentially flat on-axis response from 45Hz to above 15kHz, with almost no directivity error. Dual 56W Class D amps drive an 8” woofer and 1” tweeter with a smooth, imperceptible crossover transition. Excellent value at $498 per pair. Watch for: A resonance shows up around 18kHz and a slight dip around 1.4kHz. An electronic limiter creates measurable anomalies around 96dB, and maximum clean output tops out around 105dB SPL before heavy limiting kicks in. Some audible tweeter hiss at close range.
What the Genelec 8351B offers: 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.” Watch for: 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.
Buy the JBL 308P MKII if the price matters more than sound quality. Buy the Genelec 8351B if sound quality matters more than the price.
Specifications Side By Side
| JBL 308P MKII | Genelec 8351B | |
|---|---|---|
| Price | $498 | $9150 |
| Ranked | #26 of 66 in Large Size Powered Bookshelf Speakers | #6 of 66 in Large Size Powered Bookshelf Speakers |
| Bass Extension (-3dB) | 82Hz (measured, Audio Science Review) | 33Hz (measured, Audio Science Review) |
| Bass Extension (-10dB) | 60Hz (measured, Audio Science Review) | 28Hz (measured, Audio Science Review) |
| Dimensions | 16.5"H x 10"W x 12.1"D (419.1 x 254 x 307.3 mm) | 17"H x 11.3"W x 10.9"D (431.8 x 287 x 276.9 mm) |
| Frequency Response | 45Hz - 20kHz (+/-3dB) (Manufacturer specified) | 32Hz - 40kHz (±1.5dB) (Manufacturer specified) |
| Weight | not published by manufacturer | 31.1 lbs / 14.1 kg each |
| Drivers | 8" woofer, 1" neodymium tweeter | 8.6" woofer, 5" coaxial with tweeter midrange, 0.75" (19mm) coaxial tweeter |
| App | No | Yes (GLM) |
| EQ | No | Yes (via GLM software) |
| DSP | No | Yes |
| Output Power | 112W total | 550w Per Speaker |
| Inputs | - | XLR |
| Bluetooth | - | No |
| Max SPL | - | 113dB @ 1m |
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- Genelec 8351B vs Kali Audio IN-8 V2
- Genelec 8351B vs Focal Alpha 65 EVO
Prices on this page were last checked August 25, 2026 at 6:19 AM UTC. Product prices and availability are accurate as of that date/time and are subject to change; the price and availability shown on Amazon at the time of purchase will apply to the purchase of this product.
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The Two Speakers In Full
JBL 308P MKII: $498 Bhphotovideo eBay
Pros: CEA2034 spinorama shows an essentially flat on-axis response from 45Hz to above 15kHz, with almost no directivity error. Dual 56W Class D amps drive an 8” woofer and 1” tweeter with a smooth, imperceptible crossover transition. Excellent value at $498 per pair.
Cons: A resonance shows up around 18kHz and a slight dip around 1.4kHz. An electronic limiter creates measurable anomalies around 96dB, and maximum clean output tops out around 105dB SPL before heavy limiting kicks in. Some audible tweeter hiss at close range.
Full JBL 308P MKII review and specifications →
| App | No |
|---|---|
| Bass Extension (-10dB) | 60Hz (measured, Audio Science Review) |
| Bass Extension (-3dB) | 82Hz (measured, Audio Science Review) |
| DSP | No |
| Dimensions | 16.5"H x 10"W x 12.1"D (419.1 x 254 x 307.3 mm) |
| Drivers | 8" woofer, 1" neodymium tweeter |
| EQ | No |
| Frequency Response | 45Hz - 20kHz (+/-3dB) (Manufacturer specified) |
| Output Power | 112W total |
| Weight | not published by manufacturer |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
Genelec 8351B: $9150 Bhphotovideo eBay
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 |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons