Short answer: the Miller & Kreisel IW150. Both are rated 3.6/5 for sound quality (#17 and #16 of 28 in-wall speakers), and the Miller & Kreisel IW150 costs $4,998 against $7,259.90 for the JBL Synthesis SCL-4, with sound quality a draw, the lower price decides it.
The JBL Synthesis SCL-4 is the more accurate, deeper-bass pick. A compact in-wall speaker with a horn tweeter, very even coverage and bi-amp terminals for custom theater installs. Its measured preference score, a predictor of how neutral it sounds, is 3.56 against 2.88 for the Miller & Kreisel IW150. Its bass reaches about 83.7Hz before falling 3dB, against 95.2Hz for the Miller & Kreisel IW150. The tradeoff: Bass is the weakest here, at 83.7Hz for -3dB and about 61.9Hz for -10dB in free air, so it needs a subwoofer.
The case for the Miller & Kreisel IW150: An in-wall speaker with three tweeters beside two woofers, designed to spread sound evenly across a room from one opening. Watch for: Bass is thin: measured -3dB is 95.2Hz and -6dB is 82.0Hz, and Miller & Kreisel rates it only to 80Hz, so a subwoofer is required, and even with a perfect subwoofer the score reaches only 6.32.
Buy the Miller & Kreisel IW150. Both are rated the same for sound quality, and it costs $2,261.90 less than the JBL Synthesis SCL-4.
Still deciding? The full Passive Home rankings cover every ranked option.
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
| JBL Synthesis SCL-4 | Miller & Kreisel IW150 | |
|---|---|---|
| Price | $7,259.90 per pair | $4,998 per pair |
| Ranked | #16 of 28 in In-Wall & In-Ceiling Speakers | #17 of 28 in In-Wall & In-Ceiling Speakers |
| Drivers | 7” aluminum matrix cone woofer, 1” 2409H compression driver on HDI horn (2-way) | 2x 5.25” polypropylene bass/midrange drivers, 3x 1” soft fabric dome tweeters |
| Enclosure | In-wall, integrated MDF back box | In-wall |
| Dimensions | 25”H x 16.1”W x 3.7”D (636 x 409 x 93 mm) | 13.9”H x 12.2”W (354 x 311 mm) baffle (95mm mounting depth) |
| Weight | 27.6 lbs (12.51 kg) | 18.7 lbs (8.5 kg) |
| Sensitivity | 91dB (2.83V/1m) | 90dB |
| Impedance | 6 ohms | 4 ohms |
| Power Handling | 200W RMS maximum recommended amplifier power | 25-400W recommended amplifier power |
| Frequency Response | 45Hz-33kHz -6dB (manufacturer, on-axis) | 80Hz-20kHz +/-3dB (manufacturer) |
| Crossover Frequency | 1.3kHz | - |
| Bass Extension (-3dB) | 83.7Hz (measured, JBL data on spinorama.org) | 95.2Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-10dB) | 61.9Hz (measured, JBL data on spinorama.org) | 68.7Hz (measured, Erin’s Audio Corner) |
| Spinorama Preference Score | 3.56 | 2.88 |
| Spinorama Preference Score with Perfect Sub | 6.55 | 6.32 |
| DIY Kit | No | No |
| Mounting Cutout | - | 288W x 331H mm |
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