Short answer: the Infinity Primus 360 for measured linearity, the Q Acoustics 5040 for modern driver design. This 2005 three-way tower holds up with on-axis linearity within about +/-2dB, though its rated 93dB sensitivity runs 3-4dB optimistic against a measured 89.4dB average. The 5040’s C3 profile gives smooth midrange integration and controlled breakup, but a mid-bass scoop around 200Hz leaves it roughly 6dB below the mean SPL.
Buy the Q Acoustics 5040 new; the Infinity Primus 360 is no longer sold new, so it only makes sense as a used find.
Want more options? Browse the full Passive Home rankings.
Specifications Side By Side
| Q Acoustics 5040 | Infinity Primus 360 | |
|---|---|---|
| Price | $2,472.98 per pair | $650 per pair Discontinued |
| Ranked | #41 of 74 in Large Size Floorstanding Speakers | #40 of 74 in Large Size Floorstanding Speakers |
| Bass Extension (-10dB) | 39Hz (measured, Erin’s Audio Corner) | 37Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-3dB) | 70Hz (measured, Erin’s Audio Corner) | 53Hz (measured, Erin’s Audio Corner) |
| Dimensions | 38.1”H x 11.5”W x 14.2”D (967 x 293 x 361 mm) | 39” x 8.2” x 13” (990 x 208 x 330 mm) |
| Impedance | 6 ohms nominal (3.0 ohms minimum, measured by Erin’s Audio Corner) | 8 ohms nominal, 3.5 ohms minimum (measured, Erin’s Audio Corner) |
| Sensitivity | 91.5dB (measured average, Erin’s Audio Corner) | 89.4dB (measured, Erin’s Audio Corner; 93dB manufacturer specified) |
| Drivers | 0.88 in. decoupled dome tweeter, twin 5.0 in. C3 Continuous Curved Cone woofers | Two 6.5” mid-woofers, 4” mid-range, 0.75” dome tweeter |
| Weight | 39.7 lbs (18.0 kg) each | 48.5 lbs (22 kg) each |
| Woofer Cabinet | ported, rear | - |
| Spinorama Preference Score | 3.80 | 4.97 |
| Spinorama Preference Score with Perfect Sub | 6.41 | 7.10 |
| DIY Kit | No | No |
| Frequency Response | - | 38Hz - 20kHz (±3dB, Manufacturer specified) |
| Crossover Frequency | - | 350Hz & 3.3kHz, 24dB/octave |
| Recommended Power | - | 10-200W |
Related Speaker Comparisons
More top alternatives to Infinity Primus 360:
- Revel F226Be vs Infinity Primus 360
- KEF Reference 203 vs Infinity Primus 360
- JBL HDI-3800 vs Infinity Primus 360
- Focal Chora 816 vs Infinity Primus 360
- Revel F208 vs Infinity Primus 360
Prices on this page were last checked October 2, 2026 at 10:18 PM 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.
As an eBay Partner, we may be compensated if you make a purchase.
The Two Speakers In Full
Q Acoustics 5040: $2,472.98 per pair Amazon eBay
Pros: C3 (Continuous Curved Cone) driver profile technology provides smooth midrange integration, controlled cone breakup, and improved bass damping. High voltage sensitivity (91.5dB SPL at 2.83V/1m) allows loud listening with low-to-moderate amplifier wattage. Cabinet features Point-to-Point (P2P) internal bracing and Helmholtz Pressure Equalizer (HPE) tubes to suppress internal standing waves and panel vibrations. Measured bass extension of 70Hz (-3dB), with a measured sensitivity of 91.5dB.
Cons: Free-field frequency response exhibits a noticeable mid-bass scoop around 200Hz (~6dB lower than mean SPL), causing an F3 of 70Hz (F10 of 39Hz) in open space and requiring boundary placement (11-22 inches from front wall) to reinforce upper bass output. Measurements indicate an enclosure resonance near 300Hz visible in sound power data. Minimum impedance drops to 3.0 ohms, demanding a stable 4-ohm rated amplifier despite high sensitivity.
Full Q Acoustics 5040 review and specifications →
| Bass Extension (-10dB) | 39Hz (measured, Erin’s Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 70Hz (measured, Erin’s Audio Corner) |
| DIY Kit | No |
| Dimensions | 38.1”H x 11.5”W x 14.2”D (967 x 293 x 361 mm) |
| Drivers | 0.88 in. decoupled dome tweeter, twin 5.0 in. C3 Continuous Curved Cone woofers |
| Impedance | 6 ohms nominal (3.0 ohms minimum, measured by Erin’s Audio Corner) |
| Sensitivity | 91.5dB (measured average, Erin’s Audio Corner) |
| Spinorama Preference Score | 3.80 |
| Spinorama Preference Score with Perfect Sub | 6.41 |
| Weight | 39.7 lbs (18.0 kg) each |
| Woofer Cabinet | ported, rear |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
- Q Acoustics 5040 vs Klipsch Forte IV
- Q Acoustics 5040 vs KEF Q11 Meta
- Q Acoustics 5040 vs Polk Reserve R500
- Q Acoustics 5040 vs ELAC Debut 3.0 DF63
- Q Acoustics 5040 vs Klipsch RP-5000F II
- Q Acoustics 5040 vs Emotiva Airmotiv T2+
- Q Acoustics 5040 vs PSB Imagine T65
- Q Acoustics 5040 vs Polk Audio Reserve R700
- See all 41 comparisons
Infinity Primus 360: $650 per pair Discontinued eBay
Pros: A three-way tower from 2005 (two 6.5” mid-woofers, a 4” mid-range, and a 0.75” dome tweeter, 8 ohms nominal) that holds up remarkably well by modern measurement standards: on-axis linearity is within about ±2dB, and the listening window stays consistent out to roughly ±30° horizontal and ±10° vertical off the mid-range axis. Horizontal directivity is well controlled out to about ±75° before tonality starts to drift, meaning the reflected sound in a room stays close in character to the direct sound: a speaker that takes EQ well without fighting itself. Harmonic distortion measures low at both 86dB and 96dB, and multitone distortion stays under the reviewer’s 3% threshold. Silky, smooth midrange with a rich lower-midrange/upper-bass character. No mechanical issues or surround degradation found in a 20-year-old pair, and a second unit measured within about 1-1.5dB of the first, suggesting good long-term consistency for the design. Measured bass extension of 53Hz (-3dB), with a measured sensitivity of 89.4dB.
Cons: Manufacturer-spec sensitivity of 93dB runs about 3-4dB optimistic versus the measured 89.4dB average. Bass output drops off fairly quickly below about 50Hz in-room (F3 53Hz, F10 37Hz), so a subwoofer is needed for real low-end extension. Resonances show up around 170Hz, 220Hz, and 350Hz. On-axis, the lower treble can sound a bit bright or sibilant when the speaker is aimed directly at the listener; toeing out about 10-15° (rather than the more extreme 30°) gave the best balance, and some sidewall acoustic absorption further tamed a 4-5kHz peak. Placed close to the rear wall, bass gets boomy: pulling the speakers out about a foot resolves most of it, with roughly 1.5 feet from the wall as a good compromise between bass character and typical room aesthetics. Straying beyond about 25° above or below the mid-range axis introduces audible suckout. No longer in production, so it’s a used/secondhand purchase only.
Full Infinity Primus 360 review and specifications →
| Bass Extension (-10dB) | 37Hz (measured, Erin’s Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 53Hz (measured, Erin’s Audio Corner) |
| Crossover Frequency | 350Hz & 3.3kHz, 24dB/octave |
| DIY Kit | No |
| Dimensions | 39” x 8.2” x 13” (990 x 208 x 330 mm) |
| Drivers | Two 6.5” mid-woofers, 4” mid-range, 0.75” dome tweeter |
| Frequency Response | 38Hz - 20kHz (±3dB, Manufacturer specified) |
| Impedance | 8 ohms nominal, 3.5 ohms minimum (measured, Erin’s Audio Corner) |
| Recommended Power | 10-200W |
| Sensitivity | 89.4dB (measured, Erin’s Audio Corner; 93dB manufacturer specified) |
| Spinorama Preference Score | 4.97 |
| Spinorama Preference Score with Perfect Sub | 7.10 |
| Weight | 48.5 lbs (22 kg) each |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
- Infinity Primus 360 vs Linkwitz Lab LXmini
- Infinity Primus 360 vs Klipsch Forte IV
- Infinity Primus 360 vs Polk Reserve R500
- Infinity Primus 360 vs ELAC Debut 3.0 DF63
- Infinity Primus 360 vs KEF Q11 Meta
- Infinity Primus 360 vs Emotiva Airmotiv T2+
- Infinity Primus 360 vs Klipsch RP-5000F II
- Infinity Primus 360 vs PSB Imagine T65
- See all 30 comparisons