Short answer: the Infinity Primus 360 for measured linearity; the KEF Q11 Meta for a coaxial three-way with serious bass hardware. The 2005 Primus 360 holds up well, with on-axis linearity within about ±2dB, though its 93dB sensitivity spec runs 3-4dB optimistic against a measured 89.4dB average. The KEF is genuinely dark on raw on-axis and needs sidewall reflections within about 6 feet to sound neutral.
Buy the KEF Q11 Meta, since the Infinity Primus 360 is discontinued and only worth hunting down used.
Looking for alternatives? See the complete Passive Home rankings.
Specifications Side By Side
| Infinity Primus 360 | KEF Q11 Meta | |
|---|---|---|
| Price | $650 per pair Discontinued | $2,499.98 per pair |
| Ranked | #40 of 74 in Large Size Floorstanding Speakers | #44 of 74 in Large Size Floorstanding Speakers |
| Bass Extension (-10dB) | 37Hz (measured, Erin’s Audio Corner) | 29Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-3dB) | 53Hz (measured, Erin’s Audio Corner) | 60Hz (measured, Erin’s Audio Corner) |
| Drivers | Two 6.5” mid-woofers, 4” mid-range, 0.75” dome tweeter | 25mm tweeter + dual 165mm drivers |
| Sensitivity | 89.4dB (measured, Erin’s Audio Corner; 93dB manufacturer specified) | 88.6dB (measured, Erin’s Audio Corner) |
| Impedance | 8 ohms nominal, 3.5 ohms minimum (measured, Erin’s Audio Corner) | 4 ohms nominal (3.2 ohms minimum, measured, Erin’s Audio Corner) |
| Dimensions | 39” x 8.2” x 13” (990 x 208 x 330 mm) | 43.8”H x 12.5”W x 15”D (1112.8 x 317.5 x 381.0 mm) |
| Weight | 48.5 lbs (22 kg) each | 106.9 lbs (48.5 kg) |
| Frequency Response | 38Hz - 20kHz (±3dB, Manufacturer specified) | - |
| Crossover Frequency | 350Hz & 3.3kHz, 24dB/octave | - |
| Recommended Power | 10-200W | - |
| Spinorama Preference Score | 4.97 | 6.72 |
| Spinorama Preference Score with Perfect Sub | 7.10 | 8.03 |
| DIY Kit | No | No |
| Woofer Cabinet | - | ported, rear |
Related Speaker Comparisons
More worthwhile head-to-heads for 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 3, 2026 at 10:26 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
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 Q Acoustics 5040
- 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 Emotiva Airmotiv T2+
- Infinity Primus 360 vs Klipsch RP-5000F II
- Infinity Primus 360 vs PSB Imagine T65
- See all 30 comparisons
KEF Q11 Meta: $2,499.98 per pair Amazon eBay
Pros: Three-way tower design with a coaxial layout: a 3/4” aluminum dome tweeter (with KEF’s Metamaterial Absorption Technology behind it) mounted at the center of a 4” mid-range, plus three 6.5” bass drivers. Extremely linear estimated in-room response when placed correctly, thanks to a deliberately declining on-axis response paired with well-controlled directivity: a technically sound design philosophy, even though it reads as “dark” in raw anechoic on-axis measurements. In-room bass extension to about 40-50Hz when placed near a wall, thanks to extended bass-shelf tuning. Sounds excellent whether pointed directly at the listener or toed out a full 30° parallel to the back wall: unusually flexible placement. More vertical listening leeway than standard non-coaxial two-way designs, thanks to the coincident tweeter/midrange. Distortion looks good at both 86dB and 96dB, and multitone distortion holds up well too. Comes with a plinth/outrigger kit for stability given its floorstanding height (about 43-44”). Measured bass extension of 60Hz (-3dB), with a measured sensitivity of 88.6dB.
Cons: Genuinely dark-sounding on raw on-axis measurement, and needs a typical room with sidewall reflections (within about 6 feet/2 meters) to sound properly neutral: in a large room with little sidewall interaction, it may sound too dull for some listeners. Must be placed close to a rear wall (about 1 foot) to get proper bass: pulling it out to the “standard” 3-foot audiophile recommendation causes bass output to drop off noticeably. Horizontal radiation of about ±50° is narrower than the reviewer’s preferred ±60°, giving a slightly less enveloping soundstage than some rivals. Notably darker than sibling KEF models in the same product family: measures 2-5dB less top-end energy than the R3 Meta and a few dB less than the Q Concerto Meta. Minor lingering resonances appear in burst decay measurements between 500Hz-1kHz. The tweeter shows some strain at very high output volumes, a limitation the reviewer notes is common even among more budget-friendly speakers generally.
Full KEF Q11 Meta review and specifications →
| Bass Extension (-10dB) | 29Hz (measured, Erin’s Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 60Hz (measured, Erin’s Audio Corner) |
| DIY Kit | No |
| Dimensions | 43.8”H x 12.5”W x 15”D (1112.8 x 317.5 x 381.0 mm) |
| Drivers | 25mm tweeter + dual 165mm drivers |
| Impedance | 4 ohms nominal (3.2 ohms minimum, measured, Erin’s Audio Corner) |
| Sensitivity | 88.6dB (measured, Erin’s Audio Corner) |
| Spinorama Preference Score | 6.72 |
| Spinorama Preference Score with Perfect Sub | 8.03 |
| Weight | 106.9 lbs (48.5 kg) |
| Woofer Cabinet | ported, rear |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons