Short answer: the Polk Signature Elite ES20. It ranks #69 of 130 bookshelf speakers by sound quality at $359; the ATC SCM19 ranks #119 and costs $3750, so there is little reason to consider the other one.
What the Polk Signature Elite ES20 offers: A full-size, efficient 6.5-inch bookshelf pair with unusually deep bass for the price. ASR measured 41Hz estimated in-room extension, a well-damped Q of 0.66, broad horizontal coverage to roughly +/-60 degrees and a 5.54 preference score with a subwoofer. Watch for: Predicted in-room smoothness of 0.238 and directivity-index consistency of 3.81 are average rather than class-leading. The deep cabinet needs substantial shelf or stand space, and its Power Port still requires rear clearance.
What the ATC SCM19 offers: Harmonic distortion at 96dB SPL/1m stays generally low across the range aside from the spike tied to the 700-800Hz resonance. Sealed (unported) cabinet avoids port noise and resonance, and the extremely dense, heavy-duty enclosure (17.8kg/39lb each) reflects ATC’s pro-audio build standards. Watch for: Some stored energy resonance around 500-700hz, 4dB bump around 700hz. Not recommended for the price. CEA2034 spinorama and predicted in-room response both show a very uneven overall balance - a broad accentuation from midrange to treble paired with too little bass - along with directivity error. At 96dB SPL/1m, harmonic distortion tied to the 500-700Hz resonance rises to a level the reviewer says “should not be there.”
Buy the Polk Signature Elite ES20. It ranks higher for sound quality than the ATC SCM19 and costs less, so the other one has nothing left to offer.
The ATC SCM19 is not a sound-quality pick. It sits near the bottom of the 130 bookshelf speakers; there are better options higher up.
Want more options? Browse the full Passive Home rankings.
Specifications Side By Side
| Polk Signature Elite ES20 | ATC SCM19 | |
|---|---|---|
| Price | $359 per pair | $3750 per pair |
| Ranked | #69 of 130 in Large Size Bookshelf Speakers | #119 of 130 in Large Size Bookshelf Speakers |
| Enclosure | 2-way, Power Port bass-reflex | - |
| Drivers | 1" Terylene dome tweeter, 6.5" polypropylene woofer | 5.9" Super Linear Magnet cone woofer, 1" soft dome tweeter |
| Dimensions | 14.8H x 8.5W x 13.8D in | 17.2"H x 10.4"W x 11.8"D (436.9 x 264.2 x 299.7 mm) |
| Weight | 17 lbs (7.7 kg) each | 39.2 lbs (17.8 kg) each |
| Sensitivity | 86dB | 85dB (measured, Audio Science Review) |
| Impedance | 4/8-ohm compatible | 6 ohms |
| Country | United States (design) | - |
| Spinorama Preference Score | 3.60 | 3.79 |
| Spinorama Preference Score with Perfect Sub | 5.54 | 6.21 |
| Bass Extension (-10dB) | - | 34Hz (measured, Audio Science Review) |
| Bass Extension (-3dB) | - | 60Hz (measured, Audio Science Review) |
| Woofer Cabinet | - | sealed |
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Prices on this page were last checked September 16, 2026 at 12:41 AM 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
Polk Signature Elite ES20: $359 per pair B&H Photo Video eBay
Pros: A full-size, efficient 6.5-inch bookshelf pair with unusually deep bass for the price. ASR measured 41Hz estimated in-room extension, a well-damped Q of 0.66, broad horizontal coverage to roughly +/-60 degrees and a 5.54 preference score with a subwoofer.
Cons: Predicted in-room smoothness of 0.238 and directivity-index consistency of 3.81 are average rather than class-leading. The deep cabinet needs substantial shelf or stand space, and its Power Port still requires rear clearance.
Full Polk Signature Elite ES20 review and specifications →
| Country | United States (design) |
|---|---|
| Dimensions | 14.8H x 8.5W x 13.8D in |
| Drivers | 1" Terylene dome tweeter, 6.5" polypropylene woofer |
| Enclosure | 2-way, Power Port bass-reflex |
| Impedance | 4/8-ohm compatible |
| Sensitivity | 86dB |
| Spinorama Preference Score | 3.60 |
| Spinorama Preference Score with Perfect Sub | 5.54 |
| Weight | 17 lbs (7.7 kg) each |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
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- See all 44 comparisons
ATC SCM19: $3750 per pair Tmraudio eBay
Pros: Harmonic distortion at 96dB SPL/1m stays generally low across the range aside from the spike tied to the 700-800Hz resonance. Sealed (unported) cabinet avoids port noise and resonance, and the extremely dense, heavy-duty enclosure (17.8kg/39lb each) reflects ATC’s pro-audio build standards. Measured bass extension of 60Hz (-3dB), with a measured sensitivity of 85dB.
Cons: Some stored energy resonance around 500-700hz, 4dB bump around 700hz. Not recommended for the price. CEA2034 spinorama and predicted in-room response both show a very uneven overall balance - a broad accentuation from midrange to treble paired with too little bass - along with directivity error. At 96dB SPL/1m, harmonic distortion tied to the 500-700Hz resonance rises to a level the reviewer says “should not be there.”
Full ATC SCM19 review and specifications →
| Bass Extension (-10dB) | 34Hz (measured, Audio Science Review) |
|---|---|
| Bass Extension (-3dB) | 60Hz (measured, Audio Science Review) |
| Dimensions | 17.2"H x 10.4"W x 11.8"D (436.9 x 264.2 x 299.7 mm) |
| Drivers | 5.9" Super Linear Magnet cone woofer, 1" soft dome tweeter |
| Impedance | 6 ohms |
| Sensitivity | 85dB (measured, Audio Science Review) |
| Spinorama Preference Score | 3.79 |
| Spinorama Preference Score with Perfect Sub | 6.21 |
| Weight | 39.2 lbs (17.8 kg) each |
| Woofer Cabinet | sealed |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons