Audio Research DS-450M

Offered for sale is a pair of Audio Research DS450 M monobloc
stereo amplifiers in outstanding condition.  Treated very
respectfully and carefully for 2995 hours (based upon the hour meter of an
Audio Research LS27 preamplifier paired with these amps), these amplifiers were
purchased new in 2011 and were used for 3 years. They were used by
the current owner in a climate-controlled audio room with line conditioners,
surge protectors and were never abused in operation. They have been stored
for 5 years in a climate-controlled home.  The units are dent free
and have no scratches, mars or scuffs.  They have minimal dust and were
maintained by a caring owner in a HEPA filtered environment in open racks with
great cooling and were never overdriven, over-worked or otherwise
abused.  

Enough about the great condition of the units; how do they
sound?  With 450 watts into 8 ohms, they offer amazing power but don’t
overlook the nuances in music: a bit like a body builder who can also dance
ballet or Dallas Cowboy Emmitt Smith who was a hard pounding running back and
also won DWTS.  With an analog second stage, sonically, the DS450s are
Incredibly dynamic and lightening quick. They offer a “big hammer” ability when
called upon, while delivering the highly desired detail so necessary to provide
exceptional sound.  Bass is profound and deep, with great harmonics and
control. The midrange is transparent and open yet tightly focused and
transparent while offering accurate insight into the recording. Highs are
extended and have pinpoint detail without graininess.  From kick drum to
upright bass to power chords on electric guitar to acoustic guitar strings to
violins to soprano vocals to woodwinds, these amps respond with accuracy,
punch, sustain and decay.  They deliver space, location depth, clarity and
detail.  All of this works together to offer proper placement of
instruments and voices and sound staging that not only delivers the sound
locates them while filling the listening area with accuracy and detail
throughout the area and in the listeners ears.  Bass and loud passages
don't strain while mids and highs don't overchallenge the DS450s.  

When a company specializing in tube amplifiers offers a solid-state
amp, you can bet it will be something special and the DS450Ms don't
disappoint.  With your great upstream electronics (preamp, turntable/SACD,
digital device, cables, etc.), if you’ve been looking for amps with power and
sensitivity to handle what your system can provide, your search is over. 
With 450 watts of power, these amps can deliver rock or blues punch and bass
without losing the delicate touch needed to reproduce nuanced detail in vocals,
strings, flutes or ride cymbals.  A deep, wide, detailed soundstage brings
the most difficult material to life without coloring the sound by shortcomings
in the amplifiers.  One listen to these instruments tells you why Audio
Research equipment is so highly regarded.

I'll split shipping cost 50/50 with buyer for in-home
pickup/delivery.

Reviews of the amps are available on the web and below is Audio
Research’s brochure and specification information:

Audio Research
brochure

The DS450M mono amplifier adds a new level of performance and
flexibility to our Definition Series of amplifiers. Providing abundant power,
dynamics and control in a compact chassis, the DS450M rounds out the DS
amplifier lineup.

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 monoblocs 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.

Like all Audio Research products, the DS450M is made by hand in
our Plymouth, Minnesota facility. Connections are hand-soldered, not press-fit
nor wave-soldered. All metalwork, boards, transformers and major parts are
American-made and sourced locally. We take a great deal of pride in our
workmanship, and so will you.

Introduced

     2011

Original MSRP (US new retail)

     $4,995 each

Specifications

     Power output: 450W into 8 ohms (650W
into 4 ohms), 1% THD

     Power bandwidth: (-3dB points) 5Hz to
45kHz into 8 ohms

     Frequency response: (-3dB points at 1W)
5Hz to 45kHz into 8 ohms

     Input sensitivity: 2.9V RMS for rated
output (26dB Gain) single-ended or balanced

     Input impedance: 150K ohms
single-ended, 300K ohms balanced differential

     Output regulation: 0.02dB 8 ohms loaded
to open circuit

Overall negative feedback    

     Damping factor: 440

     Slew rate: 5 V/µs (20% maximum duty
cycle)

     Rise time: 8.0 µs

     Hum & noise: <300µV RMS (105 dB
below rated output IHF A-weighted)

     Power supply energy storage: 176,800 µF
total 684 Joules

     Power requirements: 100-125VAC 60Hz
(200-240VAC 50Hz) 550 watts at rated 

     output (450W into 8 ohms), 700 watts at 650W into 4 ohms,
700 watts maximum, 55 

     watts idle      

Other          

     Output current: ~35 amps peak at protective
shutdown

     Output polarity: Non-inverting from
single-ended input. Balanced pin 2+ (IEC-268)

     Dimensions: 19" (48 cm) W
(standard rack panel) x 5¼" (13.3 cm) H x 14¼" (36.2 

     cm)      D (front back panel). Optional
handles extend 1½" (3.3 cm) forward of the 3/8" 

     thick front panel. Output connectors extend 1½" behind
rear panel.

     Weight: 37.2 lbs. (16.9 kg) Net; 43.3
lbs. (19.7 kg) Shipping