I was fortunate to purchase an original example from 1979 in terrific shape. Still in its original packaging, there was plenty of dust buildup inside (see "Progress" photos) as well as a low level hum at the speakers.  You may ask, "what's so special about a 40 year old amp that make's it worth rebuilding?" 

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It's my second time with an A-27.  I have fond memories of the first one, but that one was in rough physical shape and I quickly sold it. This example would not bias properly (Power Supply Board voltage well below rating), but it still sounded good - very good - right out of the box. Even prior to rebuilding, this amp earned a spot high on my list of favorite vintage audio pieces for it's design, build, and especially sound. At 63lbs, Pioneer just got something right here. The large knobs are solid aluminum with the smaller controls protected/hidden with a thick hinged glass panel. This amp reaches deep while offering a fantastic midrange and 3-dimensional soundstage that seems to separate  instruments. And, yes, under the thick glass panel are defeatable tone controls.

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Listening compared to what other amps?

I've owned many well regarded amplifiers out of USA, Japan, France, UK, and Australia that, although very good, always left me searching for the next "audio nirvana." That list includes the likes of:

• Accuphase (E-202)

• Audiolab (8000A) 

• Audio Research (100.2)

• Ayre (V-3, AX-7E)

• First Watt (J2, F5)

• Jeff Rowland (Model 1, 3, and 102)

• Kenwood (Supreme 600)

• Krell (KSA50, KSA 100S, Altair)

• Lavardin (IS Reference)

• LFD (Zero Mk III)

• Luxman (L-550)

• Marantz (PM-95 3 exmples)

• Mark Levinson (ML-9/ML-10a, ML26, ML23.5, ML27.5, ML29)

• Pass Labs (Aleph 3)

• Pioneer (M22)

• Spectral (DMA 90)

• Threshold (400A/SL-10, SA/3)

• Yamaha (A-1, B2 VFET)

• YBA (Integre, Passion) ...

 

Setup

I partnered this A-27 with a pristine set of Natural Sound Yamaha NS-1000 Monitors (highly recommended to revisit these beryllium dome mid/tweeter 70lb 12" monitors manufactured for over two decades in Yamaha's piano factory) along with a well reviewed Marantz SA-11S2 Super Audio CD Player. Cables are Kimber Kable's Hero/WBT interconnects and 8TC speaker cables.

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Listening

Using wide variety of rock, jazz, and smooth jazz...

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                                        40 year old stock 

• Treble                              9/10 

• Midrange/Vocals          9/10 

• Deep Bass                      8/10  

• Soundstage                   9/10 

• 3D/Openness                8/10   

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                                        Rebuilt/Break in

• Treble                              10/10

• Midrange/Vocals          11/10 SUBLIME!

• Deep Bass                      9/10

• Soundstage                  10/10

• 3D/Openness               10/1​0

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