Threshold S-200
A Stasis power amp that shows up in dealer classifieds more often than in the review literature. The used prices tell their own story.
Overview
The archive's record on the Threshold S-200 is thin. There is no confirmed production span, no original retail price from the manufacturer, and no full independent bench test in the material gathered here. What survives is a paper trail of dealer listings from the early 1990s and a single trade-press notice from 1988. That notice describes the S-series bias circuitry as a family and doesn't break out the S-200 by name. Anyone chasing hard numbers on this one will come up short, and guessing to fill the gap won't help.
The record does establish that the S-200 was part of Threshold's Stasis amplifier line, and that the line got a circuit update around the start of 1988. HiFI-Stereo (January 1988, p.16) reported that Threshold had upgraded all of its Stasis power amplifiers with a new optical bias control. It uses optically coupled components to completely isolate the bias circuitry from the power stages. The same notice explained that the new arrangement allowed more accurate control of idle current by sensing the bias settings directly at the amplifier's power stages. That's a family-wide change, and the S-200 sits inside that family. But the notice names the S/500 specifically when it gets to power figures, so the S/500's 250-watt rating can't be hung on the S-200. The S-200's own output rating isn't documented in the sources here.
The most concrete evidence of the S-200's place in the market comes from the back pages of Audio. A Pennsylvania dealer called The Stereo Trading Outlet ran standing classifieds there through the early 1990s. In the February 1990 issue (p. - the listing appears in the magazine's classified section), the shop priced a used Threshold S200 at $1,395 alongside an S500 at $2,649. Three years later, in the March 1993 issue, the same dealer listed a Threshold S-200 at $995, with an SA-3 preamp at $1,595 and an S-300 updated to (E) spec at $1,899. Two data points from one dealer aren't a market index. They do suggest the S-200 traded well below its bigger Stasis siblings and drifted downward through the early '90s.
According to the 1988 trade notice, the S-series amplifiers were biased to operate in pure Class A up to roughly 20 percent of maximum output, then slid into another mode beyond that. On the S/500 that worked out to about 50 watts of Class A from a 250-watt rating. The S-200's Class A window can't be calculated from the available material, because the maximum output figure isn't documented. Anyone quoting a specific Class A wattage for this model is working from something the archive hasn't seen.
Condition and service history matter more than usual here. The bias circuitry is the core of the design, and it's the part a technician will want to verify on any used example. The archive has no service manual or owner's documentation specific to the S-200. So buyers should expect to have a tech confirm idle current and check the optically coupled bias components before running the amp into a good pair of speakers. That's ordinary caution for any 1980s Threshold with an undocumented service history, not a knock on the design.
The S-200 is a Stasis-era Threshold power amplifier with a paper trail in the dealer classifieds, a documented family-wide circuit update, and almost nothing else on the record. For a collector who wants a Threshold amp and doesn't need the S-500's rated output, it's the cheaper way in. The 1993 listing was $995 against the S-500's $2,649 in 1990. Anyone who needs verified specs before spending money should wait for a unit with documentation or a recent service invoice.
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