Audio Research DS-450M

I am selling my Audio Research DS450M
mono amps. After trying several brands and types of amps to match my Magnepan
3.6R speakers, I tried the DS450M’s on the advice of someone at AR. They were a
perfect match providing a beautiful tube like sound with plenty of bottom end
power without the high heat of tube amps. In fact, you can barely feel them
during playing. If you are looking for a powerful amp with tube like sound but
no heat and low energy consumption, then these are for you. The reason that I
am selling is that I am downsizing my home and must sell some of my gear. I
would estimate my use at less than 100  hours. They will be shipped in their original
factory cartons with all factory paper including manuals, warranty cards etc.

 I am the 2nd owner. These were manufactured in Dec. 2015  Ser#s  46784 & 85

                                              450w into 8 ohms, 650
into 4 ohms

“There are several reasons to choose
the DS450M over its stereo counterpart. The most important is
performance-based: a monaural amp simply produces a bigger, more spacious
soundstage. Also, we were able to fit a much larger power supply in the
chassis. Then there is the issue of size: the DS450M is smaller and easier to
situate than the hefty DS450 stereo amplifier. In addition to its reduced
height, the DS450M mono is 4.15 inches (10.5 cm) shallower, allowing it to fit
in a much tighter cabinet space. And, lastly, the DS450M is also perfect for
multi-channel home theater systems when you only need one more powerful and
dynamic amplifier channel. Rated power is 450 watts into 8 ohms.

The DS450M has the same chassis size as
the DSi200 and DS225, and continues the same design philosophy of other
Definition Series amplifiers. Our proprietary “hybrid Class D” all-discrete
analog switching-mosfet output technology is combined with an enormous linear
analog power supply, yielding tremendous speed and power delivery in a compact,
cool-running chassis. This remains a distinctive Audio Research design from the
ground up, forsaking the use of prepackaged “OEM” solutions common to other
switching amplifiers. Each DS450M idles at only 55 watts. One major enhancement
that allows a pair of DS450M’s to offer even higher performance than a DS450:
the energy storage of a pair of DS450M monoblocks is 1,368 joules, an increase
of 62% over the DS450. The immense power supply will jump-start the most
inefficient speakers when the music demands it.

The DS450M is a fully balanced design
with both XLR balanced inputs and RCA single-ended inputs. The rear panel
features a dual Cardas patented speaker binding post and two 12V triggers. A
12-gauge detachable power cord with a 20A IEC connector is included. In
addition to the standard all-silver version, the DS450M is also available with
a black front panel, black handles, and black top cover.

The DS450M builds on the foundation of
its siblings, with great resolving power, pinpoint imaging, and a musicality
that is immediately involving. The enormous power supply provides an authority
and sense of dynamics that are breathtaking with whatever music you choose.
Whether it is used in the most refined music system or the most over-the-top
video system, the DS450M will provide a level of performance and value that is
startling.

Tech Radar  August 2010

A conventional Class A/B amplifier offering this sort of output
would run fairly warm. But the Class D DS450, being around 93 per cent
efficient, produces hardly any heat. So, you could hide the amplifier away in a
cupboard without having to worry about ventilation.

Audio Research's website mentions this and even suggests users
might want to leave the amp permanently switched-on for best sound quality.
However, the DS450 sounds good from 'cold' and is pretty close to optimum after
about 25-30 minutes, so there's not much need. Idle, the DS450 only consumes 55
watts.

Many previous ARC power amps have been massively big and heavy,
producing huge quantities of heat, while drawing sizeable amounts of current
from the mains supply. Indeed, the company's reputation was built on
no-compromise designs that sacrificed everything for sound quality. So the
eco-friendly DS450 is a totally new departure.

HiFi
Choice, in its October 2010 review gave the DS450 stereo 5 stars in sound
quality and  5 stars for features.

https://www.absolutesounds.com/pdf/main/press/ARC%20DS450%20HFC1010web.pdf