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New, the SA-155 was an inexpensive compact integrated amplifier rather than high-end hi-fi; used examples typically trade around the low-to-mid US$30s. At US$38, this sits above the 58-listing median of US$30 and above the US$35 75th percentile, so it is ambitious unless the unit is tested, exceptionally clean, or includes desirable extras.
Its appeal is genuine: the tiny chassis includes phono and line-level inputs, tone controls, and a headphone output, making it a handy desktop or small-room amp. It works best with efficient speakers and sensible listening levels, where its modest output can sound lively and useful. For an unknown-condition example, confirm both channels, inputs, controls, speaker terminals, and headphone output before paying the premium; around US$25–US$30 would be the more convincing buy.
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.
