Simaudio Sim Audio 870A Black Amplifier - Evolution

The Simaudio 870A is the top stereo amplifier in their 
Evolution line, which is the best they make-and thus one of the best amplifiers 
anybody makes! Rated at 300 watts per channel into 8 ohms and twice that into 
4, it is a powerhouse of an amplifier with the speed and transparency of a 
smaller amp-a tricky thing to pull off. Maybe it’s the no overall negative feedback 
circuitry, or the super short signal path-who knows, but it combines strength 
with beauty. Plus, it looks great. One unlooked-for plus is that the 870A doesn’t 
run particularly hot-which tends to bode well for long-term reliability. Of 
course, I placed it on an amp stand in the open, which doesn’t hurt. I also 
like the WBT terminals, which are first-rate. From Simaudio’s website: 

Lynx circuitry which is a "no overall feedback" 
design resulting in genuine real-time amplification, a more accurate musical 
reproduction with respect to tonality, virtually non-existent IMD and the 
elimination of common phase errors resulting from feedback

Custom proprietary toroidal transformer design with lower 
magnetic, electrical and thermal loss, yielding an improved power transfer and 
lower regulation factor. The result is increased current speed and better 
dynamics

A dual-mono oversized power supply

Precision matched and fully decoupled proprietary MOON 
Bipolar output transistors with unprecedented gain linearity resulting in 
improved bass response and even more accurate sonic reproduction

A high damping factor for superior musical dynamics, 
improved signal speed and refined timbre accuracy

A very short capacitor-free signal path for a faster 
transient response

Stable to any known speaker impedance

"Class A" output to 5 watts for greater efficiency

RS-232 port for (i) full unsolicited bidirectional feedback 
and (ii) firmware updates

12 Volt trigger input/output for remote operation

4-Layer printed circuit boards with pure copper tracings for 
a much shorter signal path; This results in greater sonic accuracy and a 
dramatically improved signal-to-noise ratio

Designed to be powered up at all times for optimal 
performance

Low operating temperature for a longer than normal life 
expectancy

Ultra rigid chassis construction to minimize the effects of 
external vibrations

Accurate matching of the very finest quality electronic 
components in a symmetrical circuit design

 16 proprietary 
ideally matched Moon bipolar output transistors per channel

300,000µF of power-supply capacitance

Two 1.3kVA transformers 

18.75”W x 7.5”H x 17.5”D, 98 pounds 

In short, this is a great-sounding amplifier with the output 
capability to run pretty much any speaker. It combines a certain warmth that 
many solid-state designs seem to lack with a really enveloping soundstage and 
superb authority in the bass. It’s, for lack of a better word, musical.  The amplifier is in top condition, has only 
been used in a dedicated non-smoking environment, and comes with all original 
items-box/packing/power cord/manual/etc. I am a long-time Audiogon user and 
verified Paypal member. The amplifier is in Black. I ship FedEx or UPS if 
needed, and will split Paypal fees (roughly $200). I will also split shipping, 
as long as it’s standard/US. Expedited shipping is on the buyer.