Short answer: the Infinity Primus 360. It ranks #40 of 71 floorstanding speakers by sound quality at $650; the Magnepan LRS+ ranks #63 and costs $1300, so there is not much of a tradeoff to weigh.
What the Magnepan LRS+ offers: Thin, two-way planar-magnetic open-baffle/dipole panel design (about 48” tall, just 1” deep). Delivers a uniquely dramatic and enveloping soundstage with genuinely three-dimensional depth effects that work across all music genres, not just classical or orchestral material as commonly assumed. Extremely tight, locked-in center-phantom imaging when set up correctly. Open-baffle design avoids the “boxy” enclosure coloration of conventional cabinet speakers. Multitone distortion is remarkably consistent from low to high frequency, a characteristic the reviewer hasn’t observed in conventional cone-and-dome speakers. Compression at high output stays modest (about 0.5-1dB) through the midrange and treble, giving roughly 20-26dB of usable dynamic range in that region. At its price, a strong contender for a dedicated secondary listening room, even if not a main-system replacement. Watch for: Extremely current-hungry and power-hungry: even a pair of 600W Macintosh monoblock amplifiers only averaged about 90dB output - a robust, high-power amplifier is essentially mandatory, and budget amps won’t cut it. Bass rolls off very quickly (F3 74Hz, F10 67Hz, described as falling off “like a rock”), making a subwoofer an absolute requirement for any low-end content. A roughly 3dB dip in the mid-bass (100-300Hz) region thins out vocal body and fullness compared to a conventional bookshelf speaker. A resonance/bump around 400Hz adds a mild boxy quality, though it responds well to about 2dB of EQ correction. Extraordinarily fussy about exact positioning - both seating height (must align with the acoustic reference point between the panel’s lower tie-down points) and horizontal aiming are unusually critical; moving just a couple of inches can cause treble content above roughly 500-600Hz to nearly vanish. Distinct off-axis cancellation zones exist directly to the sides of the panel, where very little sound is audible at all. Fails badly under extreme dynamic-transient testing in the bass, and the reviewer blew fuses pushing the speaker during testing - not built for high-volume or highly dynamic playback. A genuinely different category from conventional hi-fi speakers, requiring more setup patience and experimentation than a typical monopole design.
What the Infinity Primus 360 offers: 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. Watch for: 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.
Buy the Infinity Primus 360. It ranks higher for sound quality than the Magnepan LRS+ and costs less, so there is no real case for the other one.
If sound quality matters at all to you, skip the Magnepan LRS+. It ranks near the bottom of the 71 floorstanding speakers, so look higher up the list instead.
Specifications Side By Side
| Magnepan LRS+ | Infinity Primus 360 | |
|---|---|---|
| Price | $1300 | $650.00 Discontinued |
| Ranked | #63 of 71 in Large Size Floorstanding Speakers | #40 of 71 in Large Size Floorstanding Speakers |
| Bass Extension (-10dB) | 67Hz (measured, Erin’s Audio Corner) | 37Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-3dB) | 74Hz (measured, Erin’s Audio Corner) | 53Hz (measured, Erin’s Audio Corner) |
| Sensitivity | 85.1dB (measured, Erin’s Audio Corner) | 89.4dB (measured, Erin’s Audio Corner; 93dB manufacturer specified) |
| Drivers | Full-range planar magnetic dipole panel (48" tall x 13.5" wide); quasi-ribbon design, two-way with separate mid/bass and tweeter ribbon sections | Two 6.5" mid-woofers, 4" mid-range, 0.75" dome tweeter |
| Weight | 30 lbs / 13.6 kg | 48.5 lbs (48.5 lbs / 22 kg) each |
| Woofer Cabinet | open baffle | - |
| Impedance | 4 ohms nominal, 3 ohms minimum (measured, Erin’s Audio Corner) | 8 ohms nominal, 3.5 ohms minimum (measured, Erin’s Audio Corner) |
| Dimensions | 48"H x 13.5"W x 1"D (1219.2 x 342.9 x 25.4 mm) | 39"H x 8-1/8"W x 13-7/8"D (990 x 208 x 330mm) |
| Discontinued | - | Yes |
| Frequency Response | - | 38Hz - 20kHz (±3dB, Manufacturer specified) |
| Crossovers | - | 350Hz & 3.3kHz, 24dB/octave |
| Recommended Power | - | 10-200W |
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The Two Speakers In Full
Magnepan LRS+: $1300 Magnepan eBay
Pros: Thin, two-way planar-magnetic open-baffle/dipole panel design (about 48” tall, just 1” deep). Delivers a uniquely dramatic and enveloping soundstage with genuinely three-dimensional depth effects that work across all music genres, not just classical or orchestral material as commonly assumed. Extremely tight, locked-in center-phantom imaging when set up correctly. Open-baffle design avoids the “boxy” enclosure coloration of conventional cabinet speakers. Multitone distortion is remarkably consistent from low to high frequency, a characteristic the reviewer hasn’t observed in conventional cone-and-dome speakers. Compression at high output stays modest (about 0.5-1dB) through the midrange and treble, giving roughly 20-26dB of usable dynamic range in that region. At its price, a strong contender for a dedicated secondary listening room, even if not a main-system replacement.
Cons: Extremely current-hungry and power-hungry: even a pair of 600W Macintosh monoblock amplifiers only averaged about 90dB output - a robust, high-power amplifier is essentially mandatory, and budget amps won’t cut it. Bass rolls off very quickly (F3 74Hz, F10 67Hz, described as falling off “like a rock”), making a subwoofer an absolute requirement for any low-end content. A roughly 3dB dip in the mid-bass (100-300Hz) region thins out vocal body and fullness compared to a conventional bookshelf speaker. A resonance/bump around 400Hz adds a mild boxy quality, though it responds well to about 2dB of EQ correction. Extraordinarily fussy about exact positioning - both seating height (must align with the acoustic reference point between the panel’s lower tie-down points) and horizontal aiming are unusually critical; moving just a couple of inches can cause treble content above roughly 500-600Hz to nearly vanish. Distinct off-axis cancellation zones exist directly to the sides of the panel, where very little sound is audible at all. Fails badly under extreme dynamic-transient testing in the bass, and the reviewer blew fuses pushing the speaker during testing - not built for high-volume or highly dynamic playback. A genuinely different category from conventional hi-fi speakers, requiring more setup patience and experimentation than a typical monopole design.
Full Magnepan LRS+ review and specifications →
| Bass Extension (-10dB) | 67Hz (measured, Erin's Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 74Hz (measured, Erin's Audio Corner) |
| Dimensions | 48"H x 13.5"W x 1"D (1219.2 x 342.9 x 25.4 mm) |
| Drivers | Full-range planar magnetic dipole panel (48" tall x 13.5" wide); quasi-ribbon design, two-way with separate mid/bass and tweeter ribbon sections |
| Impedance | 4 ohms nominal, 3 ohms minimum (measured, Erin's Audio Corner) |
| Sensitivity | 85.1dB (measured, Erin's Audio Corner) |
| Weight | 30 lbs / 13.6 kg |
| Woofer Cabinet | open baffle |
- Reviews, Comparisons and Sound Samples
- Erin’s Audio Corner: Grab Your Pitchforks! The Magnepan LRS+ Review You Didn’t See Coming! More from Erin’s Audio Corner →
- Erin’s Audio Review Website Magnepan LRS+
- Erin’s Audio Corner: I Tested 250 Speakers So You Don’t Have To!
- Erin’s Audio Corner Measurements (spinorama.org)
- Reddit Search for Magnepan LRS+ Review
- Head-to-Head Comparisons
Infinity Primus 360: $650.00 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.
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. Discontinued.
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) |
| Crossovers | 350Hz & 3.3kHz, 24dB/octave |
| Dimensions | 39"H x 8-1/8"W x 13-7/8"D (990 x 208 x 330mm) |
| Discontinued | Yes |
| 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) |
| Weight | 48.5 lbs (48.5 lbs / 22 kg) each |
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