Steg ST402 Review: Is 120 W x 4 Worth the Extra Length?
The Steg ST402 is the larger of the two ST series amplifiers we list, rated 120 W x 4 RMS into 4 Ω, 190 W x 4 into 2 Ω and 380 W x 2 bridged. Its Indian MRP is ₹54,990, which is ₹5,000 more than the ST401. The listing gives the same filters and inputs as the ST401, so the real question is whether 30 W more per channel justifies a chassis that is 80 mm longer and 0.8 kg heavier. This review answers that from the published numbers, covers what the listing leaves out and compares the ST402 with similar amps in our store. See it on our Steg ST402 product page.
Quick summary
Rated 120 W x 4 at 4 Ω, 190 W x 4 at 2 Ω and 380 W x 2 bridged at 4 Ω. No maximum-power figure or supply voltage is listed.
Against the ST401 that is a third more power per channel at 4 Ω, worth roughly 1.2 dB at full power.
The filters (high-pass 15 to 500 Hz, low-pass 50 to 4000 Hz, band-pass 15 to 4000 Hz), the 0 to +12 dB bass boost and the 0.5 to 9 V RMS input match the ST401.
We found no owner reviews, and the listing does not name the amplifier class.
Steg ST402 specifications
Specification | ST402 |
|---|---|
Type | 4-channel amplifier, ST series |
RMS power at 4 Ω | 120 W x 4 |
RMS power at 2 Ω | 190 W x 4 |
RMS power bridged at 4 Ω | 380 W x 2 |
Input sensitivity | 0.5 – 9 V RMS |
High-pass filter | 15 – 500 Hz |
Low-pass filter | 50 – 4000 Hz |
Band-pass filter | 15 – 4000 Hz |
Bass boost | 0 to +12 dB |
Chassis | All-aluminium |
Dimensions | 440 x 52 x 230 mm (axes not labelled) |
Weight | 4.21 kg |
India MRP | ₹54,990 |
All figures come from our store listing. We could not open Steg's own website from our research session, so none has been checked against a manufacturer page.
What the extra power actually buys
Going from 90 W to 120 W per channel is a third more power, but loudness follows a logarithm. At full power it works out to about 1.2 dB, a small step. At 2 Ω (190 W against 130 W) and bridged (380 W against 260 W) the ratio is larger, about 1.46, or roughly 1.6 dB. So the extra power is less about volume and more about matching: speakers or a subwoofer whose RMS rating sits above 90 W.
Two worked examples show the point. The JL Audio C2-650 is rated 60 W RMS with a recommended amplifier range of 15 to 100 W per channel. The ST401's 90 W sits inside that range and the ST402's 120 W sits above it, so that set would need careful gain-setting on the larger amp. On the subwoofer side, one bridged ST402 output gives 380 W into 4 Ω. That is three-quarters of the 500 W RMS rating of a JL Audio 12W3v3-4, but above the 300 W rating of a JL Audio 12W0v3-4.
What the listing leaves out
The gaps are the same as on the ST401, which we cover in the Steg ST401 review. There is no supply voltage behind the power ratings, no amplifier class, no filter slope, no word on whether the filters work per channel pair, and no mention of speaker-level inputs. The listing describes an audiophile transistor output stage and a dual differential input meant to reject head-unit noise. It gives no fuse rating or current draw, so take cable gauge and fuse size from Steg's manual. The listing offers no thermal figures either.
What owners and reviewers say about the Steg ST402
When we checked in October 2026, we found no owner reviews, forum threads or magazine tests of the ST402. The one page covering this exact model is an eBay catalogue entry. It carries specifications only, shows the amplifier as sold out and has no reviews or ratings. Its title says Class A/B, which is eBay's wording and not confirmed by Steg. If you run an ST402, tell us how it behaves in your car.
ST402 vs ST401 and similar amps in our store
The Steg ST401 (₹49,990 MRP) is rated 90 W x 4, 130 W x 4 and 260 W x 2 bridged, and measures 360 x 52 x 230 mm. Outside Steg, three four-channel amps in our store land near the ST402's power:
Deaf Bonce MLA-4120 (₹28,990 MRP): Class AB, 120, 150 and 300 W (4 Ω, 2 Ω, bridged), RCA and high-level inputs, filters from 10 Hz to 12 kHz.
Deaf Bonce MFA-4.120 (₹39,990 MRP): Class D, 120, 180 and 360 W, filters from 50 Hz to 12 kHz, in a 247 x 152 mm footprint.
Zapco HB 154D II (₹24,990 MRP): Class D, 150, 200 and 350 W, RCA and speaker-level inputs, in a 180 x 115 mm footprint.
Both Deaf Bonce amps list the same 120 W per channel at 4 Ω for a lower MRP, and the ST402's 190 W at 2 Ω and 380 W bridged are above their 150 and 180 W, and 300 and 360 W. The Zapco lists more per channel at 4 Ω and 2 Ω but less bridged. The two Class D amps are far more compact than the ST402's 440 x 230 mm footprint. Among these four, the ST402 lists the highest bridged output. The Deaf Bonce filters reach 12 kHz where the Steg's high-pass stops at 500 Hz, and the MLA-4120 and the Zapco state speaker-level inputs, which the Steg listing doesn't mention.
Who should buy it, and who shouldn't
Consider the ST402 if your speakers or subwoofer are rated above 90 W RMS, you want 380 W from a bridged output, or you plan to run 2 Ω loads that can use 190 W per channel, and you have room for a 440 mm chassis.
Look elsewhere if your speakers are rated well under 100 W RMS, where the ST401 or a smaller amp matches better, if space is tight, or if you need a confirmed speaker-level input or a tweeter high-pass above 500 Hz.
Installation notes for Indian cars
Measure the 440 mm length first, then add room for the cables at both ends. Screw the amplifier to a rigid panel, keep air around it, and remember that a closed boot in an Indian summer gets hot. VA3 Car Studio in Ghaziabad offers professional installation.
If the ST402 will drive a bridged subwoofer, we also build custom enclosures to the volume the maker publishes. For the 12W3v3-4, JL publishes 1.125 cubic feet (31.8 litres) sealed.
Price and where to buy
The Steg ST402 has an MRP of ₹54,990. VA3 Car Studio often sells below MRP, so check today's offer on the ST402 product page.
The bottom line
The Steg ST402 is the ST401 with a third more power per channel, a bigger bridged output and a longer, heavier chassis. The gain is about 1.2 dB at 4 Ω, so it matters most when your speakers or subwoofer need the rating. With no stated class, no supply voltage and no reviews, confirm the details before you buy.
Steg ST402 FAQ
What power does the Steg ST402 deliver?
The listing gives 120 W x 4 RMS at 4 ohm, 190 W x 4 at 2 ohm and 380 W x 2 bridged at 4 ohm. It lists no maximum-power figure and no supply voltage for those ratings.
Is the ST402 much louder than the ST401?
On paper, about 1.2 dB louder at 4 ohm, because 120 W is a third more than 90 W. That is a small step. The real differences are speaker and subwoofer matching, the bridged output and size.
Is the ST402 a Class A/B amplifier?
Our listing doesn't name the class. An eBay catalogue entry for the ST402 says Class A/B in its title, but that is eBay's wording and is not confirmed by Steg.
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