Short answer: the Klipsch RP-600M II. It ranks #74 of 130 bookshelf speakers by sound quality at $449.99; the JBL 4309 ranks #96 and costs $2200, so there is little reason to consider the other one.
What the Klipsch RP-600M II offers: Redesigned waveguide extends flush to the baffle edge, reducing diffraction compared to the original RP-600M. Roughly 10-20° wider horizontal radiation than the original, giving more soundstage envelopment while retaining precise imaging. A major step up in overall tonal neutrality compared to the original RP-600M, largely eliminating that model’s midrange resonance issues. Unusually, sounds better with the grille on - the grille smooths out the elevated treble rather than degrading the sound, a rare trait among speakers the reviewer has tested. More refined back-panel hardware, including anodized binding posts and jumper cables for optional bi-amping. Responds well to EQ correction (verified using measurement software and a miniDSP), letting the on-axis response be made genuinely linear. Watch for: On-axis, the treble runs notably hot - even hotter than the original RP-600M in some respects - and needs about 20° of toe-out or the grille installed to sound balanced. Horizontal dispersion is very slightly less linear across angles than the original RP-600M, a minor trade-off for the wider overall radiation pattern. Klipsch’s marketed sensitivity (about 94.5dB) is, like the original, a half-space rating roughly 9dB above the anechoic reality (closer to 85-86dB). In-room bass rolls off around 60Hz in practice, and a 120Hz boost paired with a midrange scoop gives kick drums their “tambour” without real low-end weight - a subwoofer is still recommended. Vertical listening tolerance is limited to about ±10° from the tweeter axis. Toeing the speaker out for better on-axis tonality (rather than using the grille) introduces slightly more diffuse imaging from added sidewall reflections.
What the JBL 4309 offers: A compact front-ported JBL monitor with an HDI horn, compression driver, 6.5-inch pulp woofer and adjustable UHF level. The local snapshot records 42Hz extension, a 2.56 raw score and 4.57 with a subwoofer. Watch for: Measured preference is modest for a roughly $2,200 pair, and the four-ohm load needs solid amplification. The horn’s controlled dispersion provides less room-filling width than some conventional dome designs.
Buy the Klipsch RP-600M II. It ranks higher for sound quality than the JBL 4309 and costs less, so the other one has nothing left to offer.
Looking for alternatives? See the complete Passive Home rankings.
Specifications Side By Side
| Klipsch RP-600M II | JBL 4309 | |
|---|---|---|
| Price | $449.99 per pair | $2,200 per pair |
| Ranked | #74 of 130 in Large Size Bookshelf Speakers | #96 of 130 in Large Size Bookshelf Speakers |
| Bass Extension (-10dB) | 41Hz (measured, Erin's Audio Corner) | - |
| Bass Extension (-3dB) | 70Hz (measured, Erin's Audio Corner) | - |
| Dimensions | 15.7"H x 8"W x 12.5"D (398.8 x 203.2 x 317.5 mm) | 16.5H x 10.25W x 9D in |
| Impedance | 8 ohms nominal (3.5 ohms minimum above 80Hz, measured by Erin's Audio Corner) | 4 ohms |
| Sensitivity | 86dB (measured, Erin's Audio Corner) | 87dB |
| Drivers | 6.5" Cerametallic cone woofer, 1" titanium LTS vented tweeter with Tractrix horn | 1-inch compression driver on HDI horn, 6.5-inch pulp woofer |
| Weight | 13 lbs (5.9 kg) each | 24.3 lbs (11 kg) each |
| Woofer Cabinet | ported | - |
| Spinorama Preference Score | 4.75 | 2.56 |
| Spinorama Preference Score with Perfect Sub | 6.88 | 4.57 |
| Enclosure | - | 2-way front-ported |
| Frequency Response | - | 42Hz-30kHz (-6dB) |
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- Klipsch RP-600M II vs TAD Compact Reference One (CR1TX)
- Klipsch RP-600M II vs Perlisten S4b
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- Klipsch RP-600M II vs GR-Research NX-Studio
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The Two Speakers In Full
Klipsch RP-600M II: $449.99 per pair Amazon eBay
Pros: Redesigned waveguide extends flush to the baffle edge, reducing diffraction compared to the original RP-600M. Roughly 10-20° wider horizontal radiation than the original, giving more soundstage envelopment while retaining precise imaging. A major step up in overall tonal neutrality compared to the original RP-600M, largely eliminating that model’s midrange resonance issues. Unusually, sounds better with the grille on - the grille smooths out the elevated treble rather than degrading the sound, a rare trait among speakers the reviewer has tested. More refined back-panel hardware, including anodized binding posts and jumper cables for optional bi-amping. Responds well to EQ correction (verified using measurement software and a miniDSP), letting the on-axis response be made genuinely linear. Measured bass extension of 70Hz (-3dB), with a measured sensitivity of 86dB.
Cons: On-axis, the treble runs notably hot - even hotter than the original RP-600M in some respects - and needs about 20° of toe-out or the grille installed to sound balanced. Horizontal dispersion is very slightly less linear across angles than the original RP-600M, a minor trade-off for the wider overall radiation pattern. Klipsch’s marketed sensitivity (about 94.5dB) is, like the original, a half-space rating roughly 9dB above the anechoic reality (closer to 85-86dB). In-room bass rolls off around 60Hz in practice, and a 120Hz boost paired with a midrange scoop gives kick drums their “tambour” without real low-end weight - a subwoofer is still recommended. Vertical listening tolerance is limited to about ±10° from the tweeter axis. Toeing the speaker out for better on-axis tonality (rather than using the grille) introduces slightly more diffuse imaging from added sidewall reflections.
Full Klipsch RP-600M II review and specifications →
| Bass Extension (-10dB) | 41Hz (measured, Erin's Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 70Hz (measured, Erin's Audio Corner) |
| Dimensions | 15.7"H x 8"W x 12.5"D (398.8 x 203.2 x 317.5 mm) |
| Drivers | 6.5" Cerametallic cone woofer, 1" titanium LTS vented tweeter with Tractrix horn |
| Impedance | 8 ohms nominal (3.5 ohms minimum above 80Hz, measured by Erin's Audio Corner) |
| Sensitivity | 86dB (measured, Erin's Audio Corner) |
| Spinorama Preference Score | 4.75 |
| Spinorama Preference Score with Perfect Sub | 6.88 |
| Weight | 13 lbs (5.9 kg) each |
| Woofer Cabinet | ported |
- Links
- Reviews, Comparisons and Sound Samples
- Erin’s Audio Corner: The Truth about Klipsch’s “NEW” Sound. RP-600M Update. More from Erin’s Audio Corner →
- Erin’s Audio Corner Website Klipsch RP-600M II
- GR-Research: We Bought The "NEW" RP-600M II Is KLIPSCH Listening?! More from GR-Research →
- Erin’s Audio Corner: 5 AWESOME SPEAKERS Under $1000 You Won’t Regret
- Erin’s Audio Corner Measurements (spinorama.org)
- Head-to-Head Comparisons
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- Klipsch RP-600M II vs JBL 708i
- Klipsch RP-600M II vs JBL Studio 630
- Klipsch RP-600M II vs PS Audio Aspen FR5
- Klipsch RP-600M II vs Behringer B2030P
- Klipsch RP-600M II vs Theory Audio sb25
- See all 116 comparisons
JBL 4309: $2,200 per pair eBay
Pros: A compact front-ported JBL monitor with an HDI horn, compression driver, 6.5-inch pulp woofer and adjustable UHF level. The local snapshot records 42Hz extension, a 2.56 raw score and 4.57 with a subwoofer.
Cons: Measured preference is modest for a roughly $2,200 pair, and the four-ohm load needs solid amplification. The horn’s controlled dispersion provides less room-filling width than some conventional dome designs.
Full JBL 4309 review and specifications →
| Dimensions | 16.5H x 10.25W x 9D in |
|---|---|
| Drivers | 1-inch compression driver on HDI horn, 6.5-inch pulp woofer |
| Enclosure | 2-way front-ported |
| Frequency Response | 42Hz-30kHz (-6dB) |
| Impedance | 4 ohms |
| Sensitivity | 87dB |
| Spinorama Preference Score | 2.56 |
| Spinorama Preference Score with Perfect Sub | 4.57 |
| Weight | 24.3 lbs (11 kg) each |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons