Short answer: the Monolith THX-365IW. It ranks #7 of 18 in-wall speakers by sound quality, rated 4.0/5, at $999.98; the JBL Synthesis SCL-7 ranks #11, rated 3.7/5, and costs $2,419.90, which makes this an easy call rather than a real tradeoff.
Why pick 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.
What the JBL Synthesis SCL-7 does well: Audio Science Review measured a 1.88 directivity-index deviation, among the most consistent off-axis behavior of the JBL Synthesis in-walls, and 0.60 listening-window smoothness. The catch: The response sits in a wide 4.1dB reference band with 0.43dB average on-axis deviation, so tonal balance is less even than the SCL-6.
Buy the Monolith THX-365IW. It is rated higher for sound quality than the JBL Synthesis SCL-7 and costs less, which makes it the one to get unless you need something the other one does better.
Looking for alternatives? See the complete Passive Home rankings.
Specifications Side By Side
| Monolith THX-365IW | JBL Synthesis SCL-7 | |
|---|---|---|
| Price | $999.98 per pair | $2,419.90 per pair |
| Ranked | #7 of 18 in In-Wall & In-Ceiling Speakers | #11 of 18 in In-Wall & In-Ceiling Speakers |
| Drivers | 2x 6.5” high-excursion long-fiber pulp cone woofers, 2” silk dome midrange, 1” silk dome tweeter (3-way) | Two 5.25” aluminum matrix cone woofers, 1” 2410H-2 compression driver on HDI horn (2-way) |
| Enclosure | In-wall, passive 3-way with dog-ear mounting tabs | In-wall, open back |
| Dimensions | 22.7”H x 11.1”W x 3.8”D (577 x 282 x 97 mm) | 19.1”H x 7.3”W x 3.9”D (486 x 186 x 99 mm) (93mm mounting depth) |
| Weight | 19.6 lbs (8.9 kg) | 12.6 lbs (5.72 kg) |
| Sensitivity | 89.5dB | 88dB (2.83V/1m, 2pi anechoic) |
| Impedance | 4 ohms nominal (about 2.9 ohm minimum) | 4 ohms |
| Power Handling | 160W maximum | 25-150W recommended amplifier power |
| Crossover Frequency | 550Hz, 1,900Hz (4th-order Linkwitz-Riley) | 2.0kHz |
| Warranty | 5 years | - |
| Certification | THX Ultra | - |
| Bass Extension (-3dB) | 54.6Hz (measured, Audio Science Review) | 67.4Hz (measured, spinorama.org ASR data) |
| Bass Extension (-10dB) | 31.1Hz (measured, Audio Science Review) | 42.3Hz (measured, spinorama.org ASR data) |
| Spinorama Preference Score | 5.23 | 3.46 |
| Spinorama Preference Score with Perfect Sub | 7.64 | 6.21 |
| DIY Kit | No | No |
| Mounting Cutout | - | 157 x 458mm (6.18 x 18.03 in) |
| Frequency Response | - | 55Hz-30kHz -6dB (manufacturer, 2pi) |
Related Speaker Comparisons
More worthwhile head-to-heads for Monolith THX-365IW:
- Revel W553L vs Monolith THX-365IW
- Monolith THX-365IW vs KEF CI200RR-THX
- Monolith THX-365IW vs KEF CI130.2CR
- JBL Synthesis SCL-7 vs KEF CI200RR-THX
- JBL Synthesis SCL-6 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
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
JBL Synthesis SCL-7: $2,419.90 per pair Audio Advice eBay
Pros: Audio Science Review measured a 1.88 directivity-index deviation, among the most consistent off-axis behavior of the JBL Synthesis in-walls, and 0.60 listening-window smoothness. The preference score rises from 3.46 to 6.21 with a subwoofer. Two 5.25-inch aluminum woofers and a 2410H-2 compression driver on JBL’s imaging horn give bass to 67.4Hz at -3dB and about 42.3Hz at -10dB in free air, and at $1210 each it is the least expensive way into the JBL Synthesis in-wall range. Measured bass extension of 67.4Hz (-3dB).
Cons: The response sits in a wide 4.1dB reference band with 0.43dB average on-axis deviation, so tonal balance is less even than the SCL-6. The 3.46 standard score is low without a subwoofer. At 88dB it is 3dB less sensitive than its siblings, and the 4 ohm load needs a capable amplifier.
Full JBL Synthesis SCL-7 review and specifications →
| Bass Extension (-10dB) | 42.3Hz (measured, spinorama.org ASR data) |
|---|---|
| Bass Extension (-3dB) | 67.4Hz (measured, spinorama.org ASR data) |
| Crossover Frequency | 2.0kHz |
| DIY Kit | No |
| Dimensions | 19.1”H x 7.3”W x 3.9”D (486 x 186 x 99 mm) (93mm mounting depth) |
| Drivers | Two 5.25” aluminum matrix cone woofers, 1” 2410H-2 compression driver on HDI horn (2-way) |
| Enclosure | In-wall, open back |
| Frequency Response | 55Hz-30kHz -6dB (manufacturer, 2pi) |
| Impedance | 4 ohms |
| Mounting Cutout | 157 x 458mm (6.18 x 18.03 in) |
| Power Handling | 25-150W recommended amplifier power |
| Sensitivity | 88dB (2.83V/1m, 2pi anechoic) |
| Spinorama Preference Score | 3.46 |
| Spinorama Preference Score with Perfect Sub | 6.21 |
| Weight | 12.6 lbs (5.72 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons