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Threshold T-400 "Almost Vintage" Amplifier - Pure Class A POWER

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Pickup currently unavailable at SkyFi 479

Threshold T-400 Almost Vintage Amplifier - Pure Class A Power

Threshold T-400 "Almost Vintage" Amplifier - Pure Class A POWER

SkyFi 479

Pickup currently unavailable

479 South Broad Street
Glen Rock NJ 07452
United States


Founded by Nelson Pass in 1974, Threshold is well-known in the audiophile community. This is one of their higher-end "almost vintage" amplifiers.

It's also designed to run in full Class A mode, which many strongly believe is *the absolute* best sounding way to run an amplifier. If you search "Class A vs AB" on any search engine you'll quickly learn why.

Beautiful to look at, amazing to listen to. 

Featuring both XLR and RCA inputs, plus the ability to run Mono in case you're lucky enough to have two of these! 

It's high-current design is sure to run just about any speaker with authority and ease.

On the bench we set the proper DC Offset, and made sure bias measured equal on both channels. Working exactly as as it should to full rated power.

Stereo Power Output:
150 Watts Per Channel Into 8 Ohms
300 Watts Per Channel Into 4 Ohms

Mono Power Output:
450 Watts Into 8 Ohms
900 Watts into 4 Ohms

Please see our photos for full specifications.

The SkyFi Testing Process for Solid State Amplifiers:

We start with a visual inspection of all internal components to make sure there are no signs of stress or aging. Capacitors are checked for telltale sings of bulging or leaking, resistors are checked for signs of overheating or cracking, and transistors are checked for signs of stress or damage.

We then power up the unit carefully and run a simple 1k sine wave while monitoring the output on an oscilloscope for signs of distortion or noise. Finally, we run the amplifier to its full rated power into the appropriate resistive load provided by our Sencore amplifier tester. If there is an issue, it will usually be noticeable at this point. If everything reads clean, we will often test for THD (Total Harmonic Distortion) measured by our Keithley distortion meter, and compare it against the original manufacturers specifications. The amplifier then remains powered on to "burn in" on our test bench for a few hours to make sure there are no heat related issues. If there are balanced inputs available they will be also be tested.

Final testing involves pushing actual music thorough the amplifier. We've learned over time that some issues are only noticeable to a trained ear while listening to familiar source material. Our test bench has reference vintage KEF speakers that we're very familiar with which quickly reveal any discrepancies. Some amplifiers will then move into our listening room where they are tested with our in-house reference speakers of choice.

Please click here for detailed specifics regarding our specialized packing process that separates us from the rest.



Original Box





Not Applicable


Yes - Power

Physical Condition


Working Condition


SKU: 102054