Short answer: the Monolith THX-365IW. It ranks #8 of 28 in-wall speakers by sound quality, rated 4.0/5, at $999.98; the JBL Synthesis SCL-7 ranks #14, rated 3.7/5, and costs $2,419.90, which makes this an easy call rather than a real tradeoff.
The Monolith THX-365IW is the more accurate, deeper-bass choice. An affordable three way in-wall speaker with accurate sound, deep bass for its type and a long warranty. Its measured preference score, a predictor of how neutral it sounds, is 5.23 against 3.46 for the JBL Synthesis SCL-7. Its bass reaches about 54.6Hz before falling 3dB, against 67.4Hz for the JBL Synthesis SCL-7. 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: An affordable way into a premium in-wall range, with a horn tweeter and consistent coverage across the room. 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 JBL Synthesis 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.
Prices on this page were last checked November 7, 2026 at 7:34 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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Specifications Side By Side
| Monolith THX-365IW | JBL Synthesis SCL-7 | |
|---|---|---|
| Price | $999.98 per pair | $2,419.90 per pair |
| Ranked | #8 of 28 in In-Wall & In-Ceiling Speakers | #14 of 28 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) |
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