Short answer: the Theory Audio sb25 on measured sound quality, the Klipsch RP-600M II on price. The Theory Audio sb25 ranks #70 of 130 bookshelf speakers at $1700. The Klipsch RP-600M II ranks #74 at $449.99, $1250.01 cheaper.
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 Theory Audio sb25 offers: Strong local Spinorama scores of 3.44 raw and 6.10 with a subwoofer, plus very wide, well-controlled dispersion and high output from a cabinet only 3.8 inches deep. Optional tabletop stands allow conventional bookshelf or console placement. Watch for: It requires a Theory controller-amplifier channel and model-specific DSP, making it much less straightforward than a normal passive speaker. The installation-focused form factor, per-speaker pricing and 60Hz measured extension limit value for ordinary stereo systems.
Buy the Klipsch RP-600M II if the price is the priority over sound quality, or the Theory Audio sb25 if sound quality is the priority over the price.
Want more options? Browse the full Passive Home rankings.
Specifications Side By Side
| Klipsch RP-600M II | Theory Audio sb25 | |
|---|---|---|
| Price | $449.99 per pair | $3,400 per pair |
| Ranked | #74 of 130 in Large Size Bookshelf Speakers | #70 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) | 21.5H x 9.5W x 3.8D 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) | - |
| Drivers | 6.5" Cerametallic cone woofer, 1" titanium LTS vented tweeter with Tractrix horn | Dual 5-inch carbon-fiber woofers, 1.4-inch compression driver |
| Weight | 13 lbs (5.9 kg) each | 22.9 lbs (10.4 kg) each |
| Woofer Cabinet | ported | - |
| Spinorama Preference Score | 4.75 | 3.44 |
| Spinorama Preference Score with Perfect Sub | 6.88 | 6.10 |
| Enclosure | - | Passive sealed surface/tabletop speaker |
| Frequency Response | - | 54Hz-23kHz (-6dB) |
| Coverage | - | 125 degrees conical |
| Power Handling | - | 200W AES, 800W peak |
| Maximum SPL | - | 123dB peak at 1m |
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Prices on this page were last checked September 16, 2026 at 12:41 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
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)
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Theory Audio sb25: $3,400 per pair World Wide Stereo eBay
Pros: Strong local Spinorama scores of 3.44 raw and 6.10 with a subwoofer, plus very wide, well-controlled dispersion and high output from a cabinet only 3.8 inches deep. Optional tabletop stands allow conventional bookshelf or console placement.
Cons: It requires a Theory controller-amplifier channel and model-specific DSP, making it much less straightforward than a normal passive speaker. The installation-focused form factor, per-speaker pricing and 60Hz measured extension limit value for ordinary stereo systems.
Full Theory Audio sb25 review and specifications →
| Coverage | 125 degrees conical |
|---|---|
| Dimensions | 21.5H x 9.5W x 3.8D in |
| Drivers | Dual 5-inch carbon-fiber woofers, 1.4-inch compression driver |
| Enclosure | Passive sealed surface/tabletop speaker |
| Frequency Response | 54Hz-23kHz (-6dB) |
| Impedance | 4 ohms |
| Maximum SPL | 123dB peak at 1m |
| Power Handling | 200W AES, 800W peak |
| Spinorama Preference Score | 3.44 |
| Spinorama Preference Score with Perfect Sub | 6.10 |
| Weight | 22.9 lbs (10.4 kg) each |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons