Short answer: the KEF R3. It ranks #15 of 222 bookshelf speakers by sound quality, rated 4.5/5, at $1,544.56; the Ascend Acoustics Sierra-LX ranks #37, rated 4.3/5, and costs $1,598, so there is little reason to consider the other one.
The case for the KEF R3: A three way bookshelf speaker with KEF’s coaxial driver for stable imaging across seats and very low distortion, easy to run with a modest amp. Watch for: The low-frequency alignment rolls gradually rather than delivering high-output sub-bass; KEF specifies 58Hz +/-3dB and Erin’s high-level data supports using an 80Hz subwoofer crossover.
The Ascend Acoustics Sierra-LX is the deeper-bass choice. A compact bookshelf speaker with very neutral, flat sound, a wide soundstage, and surprisingly deep bass in a bamboo cabinet. Its bass reaches about 47Hz before falling 3dB, against 58Hz for the KEF R3. Watch for: Very low sensitivity at about 81dB, so it needs a genuinely powerful amplifier to reach normal listening levels.
Buy the KEF R3. It is rated higher for sound quality than the Ascend Acoustics Sierra-LX and costs less, which makes it the one to get unless you need something the other one does better.
Still deciding? The full Passive Home rankings cover every ranked option.
A three way bookshelf speaker with KEF’s coaxial driver for stable imaging across seats and very low distortion, easy to run with a modest amp.
A compact bookshelf speaker with very neutral, flat sound, a wide soundstage, and surprisingly deep bass in a bamboo cabinet.
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Specifications Side By Side
| KEF R3 | Ascend Acoustics Sierra-LX | |
|---|---|---|
| Price | $1,544.56 per pair | $1598 per pair |
| Ranked | #15 of 222 in Large Size Bookshelf Speakers | #37 of 222 in Large Size Bookshelf Speakers |
| Bass Extension (-3dB) | Approximately 58Hz (manufacturer specified; consistent with Erin’s measured roll-off) | 47Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-10dB) | 35.2Hz (measured, Audio Science Review) | 38Hz (measured, Erin’s Audio Corner) |
| Sensitivity | Approximately 86-87dB/2.83V/1m (measured, Erin’s Audio Corner) | 81dB (2.83V/1m, measured by Erin’s Audio Corner) |
| Impedance | 8 ohms nominal; suitable for Erin’s 4/8-ohm-rated amplifier | 8 ohms nominal (5.5 ohms minimum) |
| Drivers | 1” tweeter coaxial with 5” midrange; 6.5” woofer | 6” aluminum cone woofer, 26mm dome tweeter |
| Dimensions | 16.6”H x 7.9”W x 13.2”D | 14.3” x 7.5” x 10.5” (362 x 191 x 267 mm) |
| Woofer Cabinet | ported, rear Flexible Port | Bass reflex, flared rear port |
| Weight | 29.9 lbs (13.55 kg) each | 20.9 lbs (9.5 kg) |
| Spinorama Preference Score | 6.2 (spinorama.org) | 6.63 |
| Spinorama Preference Score with Perfect Sub | 7.97 (spinorama.org) | 8.44 |
| DIY Kit | No | No |
| Power Handling | - | 350W continuous, 500W peak |
| Frequency Response | - | 28Hz - 23kHz (in-room, manufacturer specified) |
| Country | - | USA |
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