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The asking price of US$35 is slightly ambitious for this used Optimus SA-155, sitting just above the 75th percentile of US$33 from our ground-truth database of 24 comparable listings, where the median is US$30 and the 25th percentile is US$28. While not a bargain, it remains a reasonable figure for a functional unit, especially given the model’s niche appeal among vintage hi-fi collectors.
This compact mini amplifier is well-regarded for its IC-based design using the LA4440 chip and its unique, non-defeatable loudness contour that delivers extended bass response despite its small size. It offers multiple inputs including magnetic/ceramic phono, tape in/out, and tuner/aux, plus a front-panel 1/8-inch jack for portable devices. For a clean, operational listing with original-owner condition and included accessories, US$35 represents a fair buying opportunity for enthusiasts seeking a compact, characterful stereo solution.
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.
