Short answer: the Axiom Audio EP400 v3 ranks #39 of 42 subwoofers by sound quality at $599; the REL Acoustics Tzero MKIII ranks #42 at $599. Close enough in price that the sound-quality gap is the deciding factor.
What the Axiom Audio EP400 v3 offers: Its documented strengths make it a credible option in this class. Watch for: Its documented strengths make it a credible option in this class.
What the REL Acoustics Tzero MKIII offers: Its documented strengths make it a credible option in this class. Watch for: Its documented strengths make it a credible option in this class.
Buy the Axiom Audio EP400 v3. It ranks higher for sound quality than the REL Acoustics Tzero MKIII at the same price, so there is no real case for the other one.
Skip both if sound quality is the priority. There are better options higher up the 42 subwoofers.
Specifications Side By Side
| Axiom Audio EP400 v3 | REL Acoustics Tzero MKIII | |
|---|---|---|
| Price | $599 Discontinued | $599.00 |
| Ranked | #39 of 42 in Small Powered Home Subwoofers (Under 30 lbs) | #42 of 42 in Small Powered Home Subwoofers (Under 30 lbs) |
| Enclosure | sealed | sealed |
| Output SPL at 20 Hz | 90.0 dB | - |
| Output SPL at 25 Hz | 94.0 dB | 70.4 dB |
| Output SPL at 31.5 Hz | 97.0 dB | 76.6 dB |
| Output SPL at 40 Hz | 99.0 dB | 83.7 dB |
| Output SPL at 50 Hz | 99.0 dB | 89.7 dB |
| Output SPL at 63 Hz | 98.0 dB | 91.5 dB |
| Output SPL at 80 Hz | 98.0 dB | 92.1 dB |
| Output SPL at 100 Hz | 98.0 dB | 90.8 dB |
| CEA-2010-A Average (40-80Hz) | 98.5 dB | 89.2 dB |
| Dimensions | 13.7"H x 10.5"W x 16.8"D (349.2 x 266.7 x 426.7 mm) | 9.5"H x 8.5"W x 10.5"D (241.3 x 215.9 x 266.7 mm) |
| Warranty | 5 | 3 |
| Country | Canada | United Kingdom |
| Measurement Source | Audioholics | ErinsAudioCorner |
| Discontinued | Yes | - |
| Weight | 17.9 lbs / 8.1 kg | 15 lbs / 6.8 kg |
| Drivers | 8" (203mm) driver | 6.5" (165mm) driver |
| Cabinet Color | - | black, white |
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Prices on this page were last checked September 9, 2026 at 6:54 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
Axiom Audio EP400 v3: $599 Discontinued eBay
Pros: Independent CEA-2010 testing records 90.0 dB at 20 Hz and 98.5 dB through 40-80 Hz. The sealed enclosure with 8” (203mm) driver is best suited to upper-bass support in a modest room.
Cons: Deep-bass output is limited relative to its midbass result, so it is not the right choice for the lowest movie effects. The 349.2H x 266.7W x 426.7D mm cabinet and 8.1 kg mass still need deliberate placement and calibration. Discontinued.
Full Axiom Audio EP400 v3 review and specifications →
| CEA-2010-A Average (40-80Hz) | 98.5 dB |
|---|---|
| Country | Canada |
| Dimensions | 13.7"H x 10.5"W x 16.8"D (349.2 x 266.7 x 426.7 mm) |
| Discontinued | Yes |
| Drivers | 8" (203mm) driver |
| Enclosure | sealed |
| Measurement Source | Audioholics |
| Output SPL at 20 Hz | 90.0 dB |
| Output SPL at 25 Hz | 94.0 dB |
| Output SPL at 31.5 Hz | 97.0 dB |
| Output SPL at 40 Hz | 99.0 dB |
| Output SPL at 50 Hz | 99.0 dB |
| Output SPL at 63 Hz | 98.0 dB |
| Output SPL at 80 Hz | 98.0 dB |
| Output SPL at 100 Hz | 98.0 dB |
| Warranty | 5 |
| Weight | 17.9 lbs / 8.1 kg |
- Reviews, Comparisons and Sound Samples
REL Acoustics Tzero MKIII: $599.00 Amazon eBay
Pros: Independent CEA-2010 testing records 89.2 dB through 40-80 Hz. The sealed enclosure with 6.5” (165mm) driver is intended to add useful bass support without a full-size cabinet.
Cons: Without a published 20 Hz output result, deep-bass capability is less certain than its midbass figure. The 241.3H x 215.9W x 266.7D mm cabinet and 6.8 kg mass still need careful placement and calibration.
Full REL Acoustics Tzero MKIII review and specifications →
| CEA-2010-A Average (40-80Hz) | 89.2 dB |
|---|---|
| Cabinet Color | black, white |
| Country | United Kingdom |
| Dimensions | 9.5"H x 8.5"W x 10.5"D (241.3 x 215.9 x 266.7 mm) |
| Drivers | 6.5" (165mm) driver |
| Enclosure | sealed |
| Measurement Source | ErinsAudioCorner |
| Output SPL at 25 Hz | 70.4 dB |
| Output SPL at 31.5 Hz | 76.6 dB |
| Output SPL at 40 Hz | 83.7 dB |
| Output SPL at 50 Hz | 89.7 dB |
| Output SPL at 63 Hz | 91.5 dB |
| Output SPL at 80 Hz | 92.1 dB |
| Output SPL at 100 Hz | 90.8 dB |
| Warranty | 3 |
| Weight | 15 lbs / 6.8 kg |
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- Reviews, Comparisons and Sound Samples