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This compact 1990s mini amplifier, known for its versatile inputs and surprising bass response in small enclosures, appears at US$18, a price that is a strong bargain. Based on ground truth data from 24 recent comparable USD listings, the median asking price is US$30, the 25th percentile is US$28, and the 75th percentile is US$33. Since US$18 sits well below the 25th percentile of US$28, this listing represents a genuine deal that experienced buyers should not let pass.
The Optimus SA-155 is well-regarded for delivering 1.8 watts per channel into 8Ω with a full 20–25,000 Hz frequency response, plus a non-defeatable loudness contour that extends bass in small setups. Its three rear RCA inputs (phono, tuner, CD/AUX) and front 1/8-inch AUX jack make it highly adaptable for vintage turntables, CD players, or modern portable devices. At this price, even without verified condition details, the inclusivity of its features and the rarity of an original-owner unit make it a compelling buying opportunity for collectors and casual listeners alike.
Independent perspective — not a price guarantee. Always verify condition, accessories and provenance before purchase.
Optimus is best known as a RadioShack private-label audio brand rather than an independent hi-fi manufacturer. The name traces back to RadioShack’s in-house branding, with “Optimus” used on some products from the late 1960s and more broadly on audio gear in the 1980s and 1990s. It does not have a clearly identifiable standalone founder in the way a dedicated hi-fi brand would; its heritage is tied to the RadioShack retail chain in the United States.
The line covered a broad range of consumer electronics, including stereo receivers, amplifiers, speakers, cassette decks, turntables, and later some home-theater and portable audio products. Depending on the era, many Optimus components were sourced from overseas OEM manufacturers, especially in Asia, and sold through RadioShack’s stores as house-brand alternatives to mainstream consumer audio lines.
In the market, Optimus sits firmly in the mass-market and mid-fi category rather than the high-end segment. Today it is mostly remembered by vintage-audio collectors and RadioShack enthusiasts, with certain receivers and speakers drawing interest for their retro appeal and occasional value. It is not generally regarded as a boutique or audiophile-first brand, but some models remain noteworthy for solid build and nostalgic charm.
See all Optimus listings on RADAR.
