Threshold 3-Piece Combo, FET-10hl & S-1000 Monos, a PASS Masterclass

The audio engineer, Nelson Pass, is widely revered in the audiophile community for his pioneering designs of solid-state Class-A amplifiers and his generous contributions to the DIY audio hobbyist world.  Part of Pass's career landed him at Threshold, a company founded in California in 1974.  The company built a legendary reputation in the high-end audio market for its patented STASIS technology and pioneering solid-state Class-A designs...all at the hands of Nelson Pass.

The Threshold S-1000 was available at its introduction as both a stereo and dedicated mono amplifier.  The S-1000 amps were expensive in their day, and thus, rare today.  Mono examples are even harder to find.  Here we have a matched pair of S-1000 mono block amplifiers.  Combined with a stunning FET-10hl active analog preamplifier with outboard 15 volt DC power supply.  This  combo is absolutely some of the finest amplification we have had come through the shop, old or new.

The S-1000s together are a highly capable combo from Nelson Pass's revered vintage era. Utilizing a rugged bipolar architecture, the S-1000 monos deliver 500 watts RMS power into an 8 ohm load.  (Up to 100 watts of that in Class-A mode) Running a 4 ohm load? Sure, that’s easy work with more than 1,000 watts of power being transplanted to your speakers, or your welding iron. Impressive, insane, clean power.  These amps provide commanding, high-current drive capability for demanding, low-impedance loudspeaker loads.

At the core of each S-1000 lies the celebrated STASIS topology. This design splits the output stage into two distinct sections: an ultra-linear, low-power loop that operates in pure Class-A to ensure flawless voltage stability, and a high-power current-bootstrap daughter section. By decoupling the voltage and current duties, the amplifier dramatically reduces Total Harmonic Distortion (THD) while preserving dynamic headroom.

To support its massive power delivery, the S-1000 employs an over-specified linear power supply that easily handles current peaks. The physical construction is robust, incorporating extensive extruded aluminum heatsinks and dual temperature-sensitive, speed-controlled fans to maintain thermal equilibrium.  These amps are big, heavy, and built to last decades…They already have!

Not to be outdone, the FET-10hl preamplifier is a clean-running marvel all its own. Substituting heft for finesse, the FET-10hl is renown for its pristine sonic transparency. Utilizing an entirely discrete J-FET and MOSFET topology with zero op-amps in the signal path, it achieves ultra-wide bandwidth 1.5 Hz - 150 kHz gain with exceptionally low distortion. By isolating the sensitive gain modules and utilizing an over-dimensioned outboard power supply, the preamp eliminates electromagnetic interference, delivering uncompromising signal purity.

If you want big, bold, and uncompromising vintage sonic quality, this is the combo for you.

Demos are encouraged in Andover, MA.

$6,999 for the set (plus applicable shipping and/or MA sales tax)