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New, this sort of compact integrated amp was inexpensive rather than high-end, but US$25 is a strong deal against recent used asking prices: it sits at the 25th-percentile mark, well below the US$30 median and below the US$35 upper quartile. For a recognizable, genuinely useful vintage mini amp, that is bargain territory—assuming it is complete and functional.
The SA-155 is appealing because it packs line inputs, tone controls, headphone output, and a magnetic-phono input into a very small chassis. Its roughly 1.8 watts per channel are modest, but with efficient small speakers it can sound surprisingly capable and makes an excellent desktop, bedroom, or compact vintage system anchor. Since the condition is unknown, confirm that both channels work, the controls are reasonably quiet, and the power supply and speaker terminals are present; at US$25, those checks are diligence rather than a reason to walk away.
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.
