Short answer: the Ascend Acoustics Sierra-LX. It ranks #37 of 222 bookshelf speakers by sound quality, rated 4.3/5, at $1,598; the ATC SCM19 ranks #209, rated 2.4/5, and costs $3,750, so there is not much of a tradeoff to weigh.
The Ascend Acoustics Sierra-LX is the more accurate, deeper-bass option. Very neutral, flat frequency response: within about plus or minus 1.5dB ignoring one narrow dip. Its measured preference score, a predictor of how neutral it sounds, is 6.63 against 4.61 for the ATC SCM19. Its bass reaches about 47Hz before falling 3dB, against 60Hz for the ATC SCM19. The catch: Very low sensitivity at about 81dB, so it needs a genuinely powerful amplifier to reach normal listening levels.
What the ATC SCM19 does well: Harmonic distortion at 96dB SPL/1m stays generally low across the range aside from the spike tied to the 700-800Hz resonance. The catch: Some stored energy resonance around 500-700Hz, 4dB bump around 700Hz.
Buy the Ascend Acoustics Sierra-LX. It is rated higher for sound quality than the ATC SCM19 and costs less, so only choose the other one for a particular feature it does better.
Still deciding? The full Passive Home rankings cover every ranked option.
Specifications Side By Side
| Ascend Acoustics Sierra-LX | ATC SCM19 | |
|---|---|---|
| Price | $1598 per pair | $3750 per pair |
| Ranked | #37 of 222 in Large Size Bookshelf Speakers | #209 of 222 in Large Size Bookshelf Speakers |
| Bass Extension (-10dB) | 38Hz (measured, Erin’s Audio Corner) | 34Hz (measured, Audio Science Review) |
| Bass Extension (-3dB) | 47Hz (measured, Erin’s Audio Corner) | 60Hz (measured, Audio Science Review) |
| Dimensions | 14.3” x 7.5” x 10.5” (362 x 191 x 267 mm) | 17.2”H x 10.4”W x 11.8”D (436.9 x 264.2 x 299.7 mm) |
| Impedance | 8 ohms nominal (5.5 ohms minimum) | 6 ohms |
| Sensitivity | 81dB (2.83V/1m, measured by Erin’s Audio Corner) | 85dB (measured, Audio Science Review) |
| Drivers | 6” aluminum cone woofer, 26mm dome tweeter | 5.9” Super Linear Magnet cone woofer, 1” soft dome tweeter |
| Weight | 20.9 lbs (9.5 kg) | 39.2 lbs (17.8 kg) each |
| Woofer Cabinet | Bass reflex, flared rear port | sealed |
| Power Handling | 350W continuous, 500W peak | - |
| Frequency Response | 28Hz - 23kHz (in-room, manufacturer specified) | - |
| Country | USA | - |
| Spinorama Preference Score | 6.63 | 4.61 |
| Spinorama Preference Score with Perfect Sub | 8.44 | 7.03 |
| DIY Kit | No | No |
Frequency Response Compared
Both speakers’ spinorama measurements, overlaid. A flatter line is more neutral: peaks sound forward or harsh, dips sound recessed. Each curve is shifted so its average from 300 Hz to 3 kHz sits at 0 dB, so loudness differences between the two are removed and only the shape is compared. The two were measured by different sources, so small differences, especially in the bass, can come from the measurement setup rather than the speakers.
Measurement data: Ascend Acoustics Sierra-LX (measured by the manufacturer) and ATC SCM19 (measured by Audio Science Review), via spinorama.org.
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- Ascend Acoustics Sierra-LX vs KEF Reference 1 Meta
- Ascend Acoustics Sierra-LX vs GR-Research NX-Studio
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The Two Speakers In Full
Ascend Acoustics Sierra-LX: $1598 per pair Ascend Acoustics $1598 eBay
Same family: the Ascend Acoustics Sierra 1 v2 (smaller bookshelf, rated 4.7/5), the Ascend Acoustics Sierra-2EX V2 (smaller bookshelf, ranked lower, rated 4.3/5), the Ascend Acoustics Sierra Titan Tower (floorstanding, rated 4.4/5) and the Ascend Acoustics Sierra Horizon V2 (center, estimated 4.3/5). See every Ascend Sierra generation.
Pros: Very neutral, flat frequency response: within about plus or minus 1.5dB ignoring one narrow dip. Bass extension down to about 40Hz in-room despite the compact size. Wide, well-balanced soundstage (~60 degrees). Solid build quality with a laminated bamboo cabinet. Measured bass extension of 47Hz (-3dB), with a measured sensitivity of 81dB.
Cons: Very low sensitivity at about 81dB, so it needs a genuinely powerful amplifier to reach normal listening levels. Noticeable midrange distortion becomes audible above about 82-83dB SPL. A narrow dip around 3.5kHz on-axis in larger rooms without sidewall reflections: toeing the speakers out 10-20 degrees fills it in, but adds some brightness to the treble. Sensitive to listening height: sitting even slightly above or below tweeter level noticeably shifts the tonal balance.
Full Ascend Acoustics Sierra-LX review and specifications →
| Released | Apr 2022 (4 years ago) |
|---|---|
| Bass Extension (-10dB) | 38Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-3dB) | 47Hz (measured, Erin’s Audio Corner) |
| Country | USA |
| DIY Kit | No |
| Dimensions | 14.3” x 7.5” x 10.5” (362 x 191 x 267 mm) |
| Drivers | 6” aluminum cone woofer, 26mm dome tweeter |
| Frequency Response | 28Hz - 23kHz (in-room, manufacturer specified) |
| Impedance | 8 ohms nominal (5.5 ohms minimum) |
| Power Handling | 350W continuous, 500W peak |
| Sensitivity | 81dB (2.83V/1m, measured by Erin’s Audio Corner) |
| Spinorama Preference Score | 6.63 |
| Spinorama Preference Score with Perfect Sub | 8.44 |
| Weight | 20.9 lbs (9.5 kg) |
| Woofer Cabinet | Bass reflex, flared rear port |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
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- Ascend Acoustics Sierra-LX vs Ascend Acoustics Sierra-2EX V2
- Ascend Acoustics Sierra-LX vs Dynaudio Heritage Special
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- Ascend Acoustics Sierra-LX vs MoFi SourcePoint 10
- Ascend Acoustics Sierra-LX vs Wharfedale Super Linton
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ATC SCM19: $3750 per pair The Music Room $3750 eBay
Same family: the ATC SCM40 (floorstanding, estimated 2.6/5).
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 →
| Released | 2013 (13 years ago) |
|---|---|
| Bass Extension (-10dB) | 34Hz (measured, Audio Science Review) |
| Bass Extension (-3dB) | 60Hz (measured, Audio Science Review) |
| DIY Kit | No |
| 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 | 4.61 |
| Spinorama Preference Score with Perfect Sub | 7.03 |
| Weight | 39.2 lbs (17.8 kg) each |
| Woofer Cabinet | sealed |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons