Stereo Integrated Amplifier (1992-94)
Power output: 65 watts per channel into 8Ω (stereo)
Frequency response: 20Hz to 20kHz
Total harmonic distortion: 0.008%
Input sensitivity: 0.2mV (MC), 2.5mV (MM), 150mV (line)
Signal to noise ratio: 75dB (MC), 94dB (MM), 107dB (line)
Output: 150mV (line)
Dimensions: 434 x 140 x 353mm
Accessories: RC-152 remote control
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Reviewed Nov 22nd, 2013 by John Buckham
The Denon PMA-680R is a high fidelity preamp/amp for consumer use. Now a vintage stereo component is definitely worth consideration today as a high quality integrated stereo amp. Providing a nicely rounded out list of features this two channel (stereo) 65 w/pc amp was built when audio was still more than just an afterthought add on for video.
In a nutshell â€“
Sonic Accuracy: 8.5
User Friendliness: 10
Designed to be set on a table or shelf this amp, as are most amps designed for domestic use is convection cooled. The amp should be placed in a location where free airflow is available for cooling as this amp produces a moderate amount of heat. The amp was available in both black and silver finish, most imported into the USA were of the black specification. The DN-680 provides an understated elegant look for the more sophisticated owner.
The preamp section is unusually versatile with six selectable inputs and full tape dubbing facilities. Input selection is made through a row of buttons with an accompanying indicator to show at a glance the input selected. Bass and treble controls are provided with a limited +/- 8 dB gain/cut at 100 Hz and 10 KHz. Additionally, a loudness contour function is included that provides a fixed boost at 8 dB at 100 Hz and 7 dB or 10 KHz. Not the most musical centers, but effective. A â€œdirectâ€ feature is included that allows the bypassing of both the tone and loudness control circuits directing the signal path directly to the VCA volume control section. The tone control section does provide a very slight coloration to the audio when switched in. One other feature lacking is pre-out/main in jacks, if an external equalizer were to be used (think Bose 901) it would require the use of one of the tape dubbing loops provided.
The RIAA phono pre-amp conforms very closely with the RIAA equalization curve, sadly the ability to vary the cartridge loading and EQ is not provided, this feature would not be expected on an amp of this caliber however. Both Moving Magnet and Moving Coil type photo cartridges can be accommodated. If you are into vinyl you should find the preamp excellent.
Over in the amplifier section a hefty toroidial power transformer is used with ample capacity feeding oversized filter capacitors. This supply provides surprisingly muscular bass transients. The discrete amplifier section provides outstanding speaker damping and outstanding detail. The effect is a wide, deep and detailed soundstage certain to please most audiophiles.
The amp is provided with a infrared remote control that will allow for input selection and volume control through the motorized volume control. The only nit I have here is that the motor tends to turn the pot too quickly making precise volume adjustments hit and miss. This is not meant to diminish the value of the amp, you'll just need to be quick on the remote's volume button. The remote control can also operate other period Denon stereo components, such as CD players and cassette transport.
Under the cover the build quality of the PMA-680 is quite typical of high end consumer oriented electronics. Certainly up to the task, circuitry is on phoenelic printed circuit boards. The power devices are attached to a large aluminum internal heatsink. Input signal switching is through gold contact relays Volume is controlled through a high quality Alps attenuator.
The last of these were sold nearly 20 years ago, to gain the best performance from this amp a competent stereo tech should go through the unit and replace at the least the filter capacitors. If you can find a good one in clean unmolested shape it's an outstanding bargain for a top quality stereo integrated amplifier.