Focal Solo6 ST6 vs PSI Audio A21-M

Short answer: the PSI Audio A21-M for better sound quality, the Focal Solo6 ST6 for the lower price. The PSI Audio A21-M ranks #22 of 48 powered bookshelf speakers at $3720. The Focal Solo6 ST6 ranks #23 at $1499, $2221 cheaper.

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.

The case for the PSI Audio A21-M: PSI Audio deliberately skips DSP entirely, using a proprietary Coherent Phase Response analog circuit to keep phase alignment accurate without adding conversion stages, tracing its design back to the Studer A3 studio monitor. Set against that: The bass alignment measures a Q of 0.96, close to the point where a port tuned system starts to show a mild peak rather than a clean rolloff, worth knowing if placed near a wall.

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.

Specifications Side By Side

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The Two Speakers In Full

Focal Solo6 ST6: $1,499.00 B&H Photo Sweetwater

Pros: 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. Directivity control is the tightest of this entire batch (directivity_spdi_stddev 2.87), and the listening-window response is smooth (smoothness_listening_window 0.380). Bi-amped 130W total (80W Class G woofer + 50W Class AB tweeter), each driver on its own amplifier. ‘Focus Mode’ switches the cabinet to a single-driver full-range reference signature for a second mix-translation check without extra hardware. Bass reaches 46.9Hz at -3dB / 38.1Hz at -10dB, solid for a 6.5” driver.

Cons: Bass alignment Q (lfq 0.826) is on the higher side, which can correlate with a touch of extra bass fullness/looseness versus a more critically-damped alignment. XLR-only balanced input, no unbalanced/TRS or digital connectivity. No automatic DSP room correction - tuning is limited to fixed analog shelving/high-pass switches. At $1,499 each ($2,998/pair), it’s a meaningful step up from typical prosumer active monitors.

Full Focal Solo6 ST6 review and specifications →

Amplification	130W total, bi-amped (80W Class G LF + 50W Class AB HF)
Bass Extension (-10dB)	38.1Hz (measured, spinorama.org)
Bass Extension (-3dB)	46.9Hz (measured, spinorama.org)
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
Maximum Output	110dB peak at 1m

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• Links
  • Official Focal Solo6 ST6 Product Page
• Reviews, Comparisons and Sound Samples
  • Audio Science Review Measurements (spinorama.org)
  • Reddit Search for Focal Solo6 ST6 Review
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PSI Audio A21-M: $3,720 each B&H Photo

Pros: PSI Audio deliberately skips DSP entirely, using a proprietary Coherent Phase Response analog circuit to keep phase alignment accurate without adding conversion stages, tracing its design back to the Studer A3 studio monitor. The sound power directivity index tracks tightly (standard deviation 3.39) and on axis deviation measures a moderate 0.375dB average, and it reaches a measured 39.6Hz extension point with a wide 80 degree horizontal by 30 degree vertical dispersion pattern.

Cons: The bass alignment measures a Q of 0.96, close to the point where a port tuned system starts to show a mild peak rather than a clean rolloff, worth knowing if placed near a wall. Sold as a single unit rather than a pair, a stereo set runs roughly $6,000 to $7,800 depending on retailer and finish. With no DSP or room correction on board, getting the most from it depends more on room treatment and placement than with a comparable DSP equipped monitor.

Full PSI Audio A21-M review and specifications →

Bass Extension (-10dB)	33.2Hz (measured, Audio Science Review)
Bass Extension (-3dB)	39.6Hz (measured, Audio Science Review)
Country	Switzerland
Crossover Points	2.4kHz
Dimensions	9.8"H x 15.7"W x 11.8"D (250 x 400 x 300 mm) (9.9 x 15.8 x 11.9 in)
Drivers	27mm handmade dome tweeter, 172mm cone woofer
Enclosure	ported
Frequency Response	38Hz-23kHz -6dB
Max SPL	110dB short term, 121dB peak
Power Output (Watts)	335W total (280W woofer, 55W tweeter, Class A/B)
Warranty	5+1 years
Weight	28.2 lbs / 12.8 kg (28.2 lbs) each

As an eBay Partner, we may be compensated if you make a purchase.

• Links
  • PSI Audio A21-M Official Page
• Reviews, Comparisons and Sound Samples
  • Audio Science Review: PSI A21-M Monitor Review
  • Audio Science Review Measurements (spinorama.org)
  • Reddit Search for PSI Audio A21-M Review
• Head-to-Head Comparisons
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