Short answer: the PSI Audio A21-M for analog phase coherence, the Focal Solo6 ST6 for driver pedigree. The A21-M skips DSP entirely and uses a proprietary Coherent Phase Response analog circuit to keep phase alignment accurate without adding conversion stages, tracing back to the Studer A3 studio monitor. Its bass alignment Q of 0.96 is close to where a ported system starts to show a mild peak, though, while the Solo6 ST6 offers the beryllium and ‘W’ cone pairing with a higher-than-ideal bass Q.
On the Focal Solo6 ST6 side: Beryllium inverted-dome tweeter over a 6.5” ‘W’ composite sandwich-cone woofer - a low-mass, low-distortion driver combination rarely found below far pricier monitors. Watch for: Bass alignment Q is on the higher side, which can correlate with a touch of extra bass fullness/looseness versus a more critically-damped alignment.
Buy the Focal Solo6 ST6 if the price matters more than sound quality. Buy the PSI Audio A21-M if sound quality matters more than the price.
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Specifications Side By Side
| Focal Solo6 ST6 | PSI Audio A21-M | |
|---|---|---|
| Price | $2,998 per pair | $7,440 per pair |
| Ranked | #35 of 79 in Large Size Powered Bookshelf Speakers | #22 of 79 in Large Size Powered Bookshelf Speakers |
| Bass Extension (-3dB) | 46.9Hz (measured, spinorama.org) | 39.6Hz (measured, Audio Science Review) |
| Bass Extension (-10dB) | 38.1Hz (measured, spinorama.org) | 33.2Hz (measured, Audio Science Review) |
| Maximum SPL | 110dB peak at 1m | 110dB short term, 121dB peak (manufacturer specified) |
| Amplifier Power | 130W total (80W LF + 50W HF); Bi-amped (Class G LF + Class AB HF) | 335W total (280W woofer, 55W tweeter, Class A/B) |
| Drivers | 1” Beryllium inverted-dome tweeter, 6.5” “W” composite sandwich-cone woofer | 27mm handmade dome tweeter, 172mm cone woofer |
| Dimensions | 24.6 x 33.4 x 29.5cm (9.7 x 13.1 x 11.6 in) each, 13kg (28.6 lb) each | 15.7”H x 9.8”W x 11.8”D (400 x 250 x 300 mm) |
| Spinorama Preference Score | 5.32 | 6.07 |
| Spinorama Preference Score with Perfect Sub | 7.34 | 7.72 |
| Inputs | XLR | XLR (balanced analog) |
| XLR Input | Yes | Yes |
| RCA Input | No | No |
| TRS Input | No | No |
| Optical Input | No | No |
| Coaxial Input | No | No |
| USB Input | No | No |
| HDMI Input | No | No |
| AES Input | No | No |
| Aux Input | No | No |
| Bluetooth | No | No |
| Frequency Response | 40Hz - 40kHz (±3dB) (Manufacturer specified) | 38Hz-23kHz -6dB |
| Weight | 28.7 lbs (13 kg) | 28.2 lbs (12.8 kg) each |
| Enclosure | - | ported |
| Crossover Frequency | - | 2.4kHz |
| Warranty | - | 5+1 years |
| Country | - | Switzerland |
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- PSI Audio A21-M vs JBL 708P
Prices on this page were last checked October 3, 2026 at 10:26 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
Focal Solo6 ST6: $2,998 per pair B&H Photo Video eBay
Pros: ASR measured a tight 1.6dB response span from 300Hz to 5kHz and a 7.34 ideal-subwoofer score, supporting accurate midrange monitoring. The beryllium tweeter and Focus mode offer a useful professional workflow, with Focus serving as an alternate mix-check presentation. Its beryllium inverted-dome tweeter and 6.5-inch W composite sandwich-cone woofer are a low-mass, low-distortion pairing. Measured bass extension of 46.9Hz (-3dB).
Cons: The measured -3dB point is 46.9Hz, so deep-bass work benefits from a subwoofer. The standard-mode score does not apply to Focus mode. There is no automatic room-calibration system, and premium driver materials alone do not establish superior sound.
Full Focal Solo6 ST6 review and specifications →
| AES Input | No |
|---|---|
| Amplifier Power | 130W total (80W LF + 50W HF); Bi-amped (Class G LF + Class AB HF) |
| Aux Input | No |
| Bass Extension (-10dB) | 38.1Hz (measured, spinorama.org) |
| Bass Extension (-3dB) | 46.9Hz (measured, spinorama.org) |
| Bluetooth | No |
| Coaxial Input | No |
| Dimensions | 24.6 x 33.4 x 29.5cm (9.7 x 13.1 x 11.6 in) each, 13kg (28.6 lb) each |
| Drivers | 1” Beryllium inverted-dome tweeter, 6.5” “W” composite sandwich-cone woofer |
| Frequency Response | 40Hz - 40kHz (±3dB) (Manufacturer specified) |
| HDMI Input | No |
| Inputs | XLR |
| Maximum SPL | 110dB peak at 1m |
| Optical Input | No |
| RCA Input | No |
| Spinorama Preference Score | 5.32 |
| Spinorama Preference Score with Perfect Sub | 7.34 |
| TRS Input | No |
| USB Input | No |
| Weight | 28.7 lbs (13 kg) |
| XLR Input | Yes |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
PSI Audio A21-M: $7,440 per pair B&H Photo Video eBay
Pros: ASR measured 39.6Hz -3dB extension and a 2.2dB response span from 300Hz to 5kHz, giving useful bass and broadly even mids. Its 7.72 ideal-subwoofer score supports serious monitoring, with analog phase compensation offering an alternative to DSP-based systems. Measured bass extension of 39.6Hz (-3dB).
Cons: The measured tonal result is good rather than a clear advance over less costly competitors. There is no built-in automatic room-calibration system, so placement or external correction still matters. The premium construction and analog circuitry should not be mistaken for proof of better audible performance.
Full PSI Audio A21-M review and specifications →
| AES Input | No |
|---|---|
| Amplifier Power | 335W total (280W woofer, 55W tweeter, Class A/B) |
| Aux Input | No |
| Bass Extension (-10dB) | 33.2Hz (measured, Audio Science Review) |
| Bass Extension (-3dB) | 39.6Hz (measured, Audio Science Review) |
| Bluetooth | No |
| Coaxial Input | No |
| Country | Switzerland |
| Crossover Frequency | 2.4kHz |
| Dimensions | 15.7”H x 9.8”W x 11.8”D (400 x 250 x 300 mm) |
| Drivers | 27mm handmade dome tweeter, 172mm cone woofer |
| Enclosure | ported |
| Frequency Response | 38Hz-23kHz -6dB |
| HDMI Input | No |
| Inputs | XLR (balanced analog) |
| Maximum SPL | 110dB short term, 121dB peak (manufacturer specified) |
| Optical Input | No |
| RCA Input | No |
| Spinorama Preference Score | 6.07 |
| Spinorama Preference Score with Perfect Sub | 7.72 |
| TRS Input | No |
| USB Input | No |
| Warranty | 5+1 years |
| Weight | 28.2 lbs (12.8 kg) each |
| XLR Input | Yes |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons