Short answer: the Monoprice Monolith THX Compact Satellite. Both are rated 3.2/5 for sound quality (#54 and #49 of 90 bookshelf speakers), and the Monoprice Monolith THX Compact Satellite costs $249.99 against $278 for the Sony SS-CS5 M2, so with nothing between them on sound quality, price settles it.
The case for the Monoprice Monolith THX Compact Satellite: A compact sealed satellite with a 4.5-inch coaxial driver and a 20mm silk-dome tweeter mounted at its center, THX certified and built to sit with a subwoofer crossed over at 80Hz. Watch for: Bass stops at about 82Hz (-3dB) and 62Hz (-10dB), so it needs a subwoofer for any full-range use, and without one its preference score is only 3.57.
Why pick the Sony SS-CS5 M2: Added internal bracing (corners, sides, front baffle) plus an updated crossover meaningfully reduce the resonance issues that plagued the original SS-CS5, giving a smoother, more neutral character overall. The tradeoff: Mild sibilance in the 3-5kHz range stands out on S and T sounds in vocals.
Buy the Monoprice Monolith THX Compact Satellite. Both are rated the same for sound quality, and it costs $28.01 less than the Sony SS-CS5 M2.
Want more options? Browse the full Passive Home rankings.
Specifications Side By Side
| Monoprice Monolith THX Compact Satellite | Sony SS-CS5 M2 | |
|---|---|---|
| Price | $249.99 per pair | $278.00 per pair |
| Ranked | #54 of 90 in Medium Size Bookshelf Speakers | #49 of 90 in Medium Size Bookshelf Speakers |
| Sensitivity | 81dB (manufacturer specified) | 82.5dB |
| Drivers | 4.5” polypropylene woofer with coaxial 20mm silk-dome tweeter | 5.12” woofer, 0.98 in tweeter; 0.75-inch supertweeter; 0.75-inch supertweeter; 0.75-inch supertweeter; 0.75-inch supertweeter |
| Impedance | 4 ohms nominal (manufacturer specified) | 6 ohms |
| Frequency Response | 80Hz-20kHz ±3dB (manufacturer specified) | - |
| Bass Extension (-3dB) | 82Hz (measured, Erin’s Audio Corner) | 80Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-10dB) | 61.5Hz (measured, Erin’s Audio Corner) | 54Hz (measured, Erin’s Audio Corner) |
| Dimensions | 6.3”H x 6”W x 5.9”D (160 x 153 x 150 mm) | 13.2”H x 7”W x 8.7”D (335 x 178 x 220 mm) |
| Weight | 4.2 lbs (1.9 kg) each | 9.5 lbs (4.3 kg) each |
| Woofer Cabinet | sealed | ported, rear |
| Spinorama Preference Score | 3.57 | - |
| Spinorama Preference Score with Perfect Sub | 6.56 | - |
| DIY Kit | No | No |
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- Sony SS-CS5 M2 vs Ascend Sierra 1 v2
- Sony SS-CS5 M2 vs KEF LS50 Meta
- Sony SS-CS5 M2 vs XMechanik Mechano23 DIY
Prices on this page were last checked September 30, 2026 at 2:57 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
Monoprice Monolith THX Compact Satellite: $249.99 per pair Amazon Monoprice eBay
Pros: A compact sealed satellite with a 4.5-inch coaxial driver and a 20mm silk-dome tweeter mounted at its center, THX certified and built to sit with a subwoofer crossed over at 80Hz. Erin’s Audio Corner measured a listening window within a 4.0dB span from 300Hz to 5kHz, a smooth predicted in-room response (0.61 smoothness) and wide, even dispersion (about 60 degrees horizontally and 55 degrees vertically), and its preference score rises to 6.56 with an ideal subwoofer. A keyhole slot makes wall mounting easy. Measured bass extension of 82Hz (-3dB).
Cons: Bass stops at about 82Hz (-3dB) and 62Hz (-10dB), so it needs a subwoofer for any full-range use, and without one its preference score is only 3.57. Sensitivity is a low 81dB into a 4-ohm load, so it needs a capable amplifier to play loud. Out of stock at Monoprice and Amazon, with Monoprice quoting a restock date well into 2027.
Full Monoprice Monolith THX Compact Satellite review and specifications →
| Bass Extension (-10dB) | 61.5Hz (measured, Erin’s Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 82Hz (measured, Erin’s Audio Corner) |
| DIY Kit | No |
| Dimensions | 6.3”H x 6”W x 5.9”D (160 x 153 x 150 mm) |
| Drivers | 4.5” polypropylene woofer with coaxial 20mm silk-dome tweeter |
| Frequency Response | 80Hz-20kHz ±3dB (manufacturer specified) |
| Impedance | 4 ohms nominal (manufacturer specified) |
| Sensitivity | 81dB (manufacturer specified) |
| Spinorama Preference Score | 3.57 |
| Spinorama Preference Score with Perfect Sub | 6.56 |
| Weight | 4.2 lbs (1.9 kg) each |
| Woofer Cabinet | sealed |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
Sony SS-CS5 M2: $278.00 per pair Amazon eBay
Pros: Added internal bracing (corners, sides, front baffle) plus an updated crossover meaningfully reduce the resonance issues that plagued the original SS-CS5, giving a smoother, more neutral character overall. A modest mid-range dip (about 1-2dB) is present but tolerable, and the reviewer would rather have this dip than a peak in that region. Slightly deeper bass than the previous version, measuring about 2dB more output around 60Hz. Distortion drops noticeably when crossed to a subwoofer around 80-120Hz, meaningfully improving midrange clarity and detail versus running full-range. Easy to drive on a standard AVR: no need for a dedicated high-power amplifier. More modern, understated waveguide look compared to the previous version’s glossy trim. Measured bass extension of 80Hz (-3dB).
Cons: Mild sibilance in the 3-5kHz range stands out on S and T sounds in vocals. Some forwardness in the midrange noticeable on certain vocal recordings. Soundstage and sense of envelopment are comparatively flat and two-dimensional, especially next to reference-quality speakers with strong 3D imaging. Marketed as a “three-way” design mainly due to an added super-tweeter that the reviewer considers largely superfluous: it engages only at very high frequencies and adds complexity without a clearly audible benefit, when that cost might have been better spent on the main crossover. Output-limited: realistic ceiling is around the mid-90s dB SPL at a few meters, with comfortable listening closer to 75-85dB at 3-4 meters before distortion and compression become audible. Bass noticeably compresses/shelves below about 120Hz as volume increases, softening kick-drum impact at higher output. Smaller drivers and a lighter motor structure than rivals like the Polk XT20, which the reviewer generally prefers for its better directivity and higher SPL capability. Still needs a subwoofer for any real bass extension.
Full Sony SS-CS5 M2 review and specifications →
| Bass Extension (-10dB) | 54Hz (measured, Erin’s Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 80Hz (measured, Erin’s Audio Corner) |
| DIY Kit | No |
| Dimensions | 13.2”H x 7”W x 8.7”D (335 x 178 x 220 mm) |
| Drivers | 5.12” woofer, 0.98 in tweeter; 0.75-inch supertweeter; 0.75-inch supertweeter; 0.75-inch supertweeter; 0.75-inch supertweeter |
| Impedance | 6 ohms |
| Sensitivity | 82.5dB |
| Weight | 9.5 lbs (4.3 kg) each |
| Woofer Cabinet | ported, rear |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons