This is one of the most iconic product in hifi history. Not only did it establish how great solid state can sound, but it also opened the World to the wonderful genius of Nelson Pass. Although it is rated for 100W Class A, its patented dynamic bias circuitry inside will allow the amp to operate way pass 500W in Class A. Unlike some other Class A designs where it changes over to Class AB, the Threshold stays in Class A throughout. And this is where you hear the consistency of the 400A across hours of listening and power demand. It has the all finer elements of tubes but with a tighter presentation and a more “pounding” bass response. Truly magical. To fully enjoy the 400A, a fitting quality of a preamp is necessary. Preferably one that is transparent and neutral. Then pair them with a great source unit and speakers and you could be listening to a really great system that didn’t cost you an arm and a leg.
The 400A you see here is in pretty nice shape. Some nicks/scrapes on the front rack handle bars and a few scratches on the top cover are the only more noticeable cosmetic issues. Otherwise, the rest of the unit looks good. No “purpling” of the heatsinks or crazy dings. This unit was sent back to a Threshold authorized service center in NYC to be re-capped, bias and restored. No expense was spared (we paid almost $2,000) on re-setting the new life span on this amp. Now it is ready for another 20-25 years of audio bliss. The amp is a hefty piece so shipping will not come cheap but will come securely packed.