Short answer: the Revel W553L. It ranks #2 of 18 in-wall speakers by sound quality, rated 4.5/5, at $1,089.90. The Monolith THX-365IW ranks #7, rated 4.0/5, at $999.98, $89.92 cheaper, not enough of a saving to outweigh the sound-quality gap.
The case for the Revel W553L: Erin’s Audio Corner’s Klippel measurement gives a preference score of 4.84, or 7.50 with a perfect subwoofer, a strong result for an in-wall speaker at this price. The catch: At $545 each a stereo pair costs twice that, and a separate amplifier is required.
The case for the Monolith THX-365IW: Audio Science Review’s retest measured a preference score of 5.23, or 7.64 with a perfect subwoofer, with -3dB at 54.6Hz and -6dB at 42.8Hz, deep bass for an in-wall speaker. Watch for: ASR’s first measurement of this speaker scored far lower (preference score 1.33, or 5.10 with a subwoofer, with -3dB at 108Hz), so results depend heavily on how it is installed and enclosed.
Buy the Revel W553L. It is rated higher for sound quality, and saving $89.92 with the Monolith THX-365IW does not make up for the sound-quality gap.
Looking for alternatives? See the complete Passive Home rankings.
Specifications Side By Side
| Revel W553L | Monolith THX-365IW | |
|---|---|---|
| Price | $1,089.90 per pair | $999.98 per pair |
| Ranked | #2 of 18 in In-Wall & In-Ceiling Speakers | #7 of 18 in In-Wall & In-Ceiling Speakers |
| Drivers | 2x 5.25” micro-ceramic composite (MCC) woofers, 1” swiveling aluminum dome tweeter with waveguide | 2x 6.5” high-excursion long-fiber pulp cone woofers, 2” silk dome midrange, 1” silk dome tweeter (3-way) |
| Enclosure | In-wall, LCR (vertical or horizontal mounting) | In-wall, passive 3-way with dog-ear mounting tabs |
| Mounting Cutout | 163W x 359H mm | - |
| Dimensions | 15.1”H x 7.4”W (384 x 188 mm) (74mm mounting depth) | 22.7”H x 11.1”W x 3.8”D (577 x 282 x 97 mm) |
| Weight | 7.7 lbs (3.5 kg) | 19.6 lbs (8.9 kg) |
| Sensitivity | 90dB | 89.5dB |
| Power Handling | 10-150W recommended amplifier power | 160W maximum |
| Warranty | Lifetime | 5 years |
| Bass Extension (-3dB) | 64.5Hz (measured, Erin’s Audio Corner) | 54.6Hz (measured, Audio Science Review) |
| Bass Extension (-10dB) | 39.3Hz (measured, Erin’s Audio Corner) | 31.1Hz (measured, Audio Science Review) |
| Spinorama Preference Score | 4.84 | 5.23 |
| Spinorama Preference Score with Perfect Sub | 7.50 | 7.64 |
| DIY Kit | No | No |
| Impedance | - | 4 ohms nominal (about 2.9 ohm minimum) |
| Crossover Frequency | - | 550Hz, 1,900Hz (4th-order Linkwitz-Riley) |
| Certification | - | THX Ultra |
Related Speaker Comparisons
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- Monolith THX-365IW vs KEF CI200RR-THX
- Monolith THX-365IW vs JBL Synthesis SCL-7
Prices on this page were last checked September 26, 2026 at 11:14 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.
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The Two Speakers In Full
Revel W553L: $1,089.90 per pair Crutchfield eBay
Pros: Erin’s Audio Corner’s Klippel measurement gives a preference score of 4.84, or 7.50 with a perfect subwoofer, a strong result for an in-wall speaker at this price. On-axis response is smooth (0.68 smoothness) and directivity is well controlled (SPDI deviation 2.35dB), so the sound off to the sides stays close to the sound you hear straight on. Bass measures to 64.5Hz at -3dB and 51.3Hz at -6dB. The 1” aluminum dome tweeter swivels toward the listening seat, a three-position switch trims treble to suit the room, and the cabinet mounts vertically or horizontally, so it works as a left, right or center channel. Measured bass extension of 64.5Hz (-3dB).
Cons: At $545 each a stereo pair costs twice that, and a separate amplifier is required. Bass ends early for a main speaker, with -3dB at 64.5Hz, so a subwoofer is needed for music and movies. Audio Science Review’s own measurement was less flattering (preference score 4.04, -3dB at 82Hz), so results differ between test benches. Two 5.25” woofers give less output headroom than the larger Revel in-wall models.
Full Revel W553L review and specifications →
| Bass Extension (-10dB) | 39.3Hz (measured, Erin’s Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 64.5Hz (measured, Erin’s Audio Corner) |
| DIY Kit | No |
| Dimensions | 15.1”H x 7.4”W (384 x 188 mm) (74mm mounting depth) |
| Drivers | 2x 5.25” micro-ceramic composite (MCC) woofers, 1” swiveling aluminum dome tweeter with waveguide |
| Enclosure | In-wall, LCR (vertical or horizontal mounting) |
| Mounting Cutout | 163W x 359H mm |
| Power Handling | 10-150W recommended amplifier power |
| Sensitivity | 90dB |
| Spinorama Preference Score | 4.84 |
| Spinorama Preference Score with Perfect Sub | 7.50 |
| Warranty | Lifetime |
| Weight | 7.7 lbs (3.5 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
Monolith THX-365IW: $999.98 per pair Amazon Monoprice eBay
Pros: Audio Science Review’s retest measured a preference score of 5.23, or 7.64 with a perfect subwoofer, with -3dB at 54.6Hz and -6dB at 42.8Hz, deep bass for an in-wall speaker. Directivity is well controlled (SPDI deviation 2.09dB) and on-axis smoothness is 0.70. It is a THX Ultra certified three-way, with two 6.5” woofers, a dedicated 2” silk dome midrange and a 1” silk dome tweeter, rated at 89.5dB sensitivity, which ASR’s measurement confirmed at 89.4dB. The 5-year warranty is longer than most in-wall speakers get. Measured bass extension of 54.6Hz (-3dB).
Cons: ASR’s first measurement of this speaker scored far lower (preference score 1.33, or 5.10 with a subwoofer, with -3dB at 108Hz), so results depend heavily on how it is installed and enclosed. Monoprice positions it for rear and surround channels and suggests in-room speakers up front, and the ASR reviewer said he would pick something better for a front left or right. Impedance dips to about 2.9 ohms, so the amplifier needs to be comfortable with a low load. At $500 each a stereo pair costs twice that.
Full Monolith THX-365IW review and specifications →
| Bass Extension (-10dB) | 31.1Hz (measured, Audio Science Review) |
|---|---|
| Bass Extension (-3dB) | 54.6Hz (measured, Audio Science Review) |
| Certification | THX Ultra |
| Crossover Frequency | 550Hz, 1,900Hz (4th-order Linkwitz-Riley) |
| DIY Kit | No |
| Dimensions | 22.7”H x 11.1”W x 3.8”D (577 x 282 x 97 mm) |
| Drivers | 2x 6.5” high-excursion long-fiber pulp cone woofers, 2” silk dome midrange, 1” silk dome tweeter (3-way) |
| Enclosure | In-wall, passive 3-way with dog-ear mounting tabs |
| Impedance | 4 ohms nominal (about 2.9 ohm minimum) |
| Power Handling | 160W maximum |
| Sensitivity | 89.5dB |
| Spinorama Preference Score | 5.23 |
| Spinorama Preference Score with Perfect Sub | 7.64 |
| Warranty | 5 years |
| Weight | 19.6 lbs (8.9 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons