Price Paid:  $22.00 from thrift store

Summary:
-drove it home from store and i had to adjust the tuner...it was running off track - started from left at around 100mhz

-great for bedroom use

-enough power for my sansui sp 2500's

-bass is pretty nice for electronic music and hiphop, on the boomy side i suppose

-unit looks superlative

-speaker terminal offers little room for 16 awg,
-the reciever's audio inputs are too close together...monster cables couldn't fit, for those that care that is...

Strengths:
1.tuner reception 2. good sound for 22wpc

Weaknesses:
1.speaker and audio terminals 2. built quality of tuner

Similar Products Used:
marantz 2220b, sansui 2000a

Summary:
I can understand Tom and Dave's (below) enthusiasm for this interesting old receiver. I picked up a near-mint unit on e-bay for a song just for the hobbiest aspect of making an old, "obsolete" product useable again. I am the owner of a
Pioneer SX-9000 stereo receiver of the same early-70's vintage and have enjoyed the smooth, powerful sounds for a number of years.
I rigged up this old quad unit just as Tom below did, sending the decoded 5.1 signals from my Sony DVD to the 4 discrete inputs of the QX-8000a. I have no center channel in my system, and sent the .1 bass and LFE info to the 2 front main speakers through the Sony's audio set-up menu. The rears are crossed at 85hz, the fronts are run full-range, with bass sent to my dual 12" CSW powered subs low passed at 60HZ.
Yowee!! This set up sounds as good as my existing Denon AVR-95! And much simpler to use. It has bass/treble for front and back, easy to use balance and fade controls, and best of all, NO MORE DAMN ON-SCREEN MENUS to futz with just to change any minor control!
In the next week or so I plan to run the pre-out jacks on all 4 channels to a pair of old Pioneer 100WPC integrated amps to get some ommpf to my low-effiency Genesis speakers. The 22WPC of this unit would be perfect if I were running Klipsch or similar, 95db+ speakers, but power comes up just a bit short here.
This great old crock goes just great with my equally vintage Pioneer CT-F 7171 cassette deck, SG-9800 Equalizer and PD-70 CD player. All have that great polished aluminum look and simple controls.
Audio purists are probably swallowing their dentures over all this, but I find it great fun to fool with this old stuff.
And I defy any "golden ears" high-end jerk to point out any significant sonic problems with a set up like this when lisening to classic rock, modern pop or home theater.

Remote contol is the only aspect of modern A/V eqpt I really miss, at least I'm not that old or lazy so I can't get up and change the volume myself! My next purchase will be a QS decoder to enjoy pro-logic encoded video tapes.
Ancillary equiptment:(2) Pioneer SA-9800 int. amps
Sony 550D DVD
Pioneer CT-F 7171 cassette deck
Pioneer SG-9800 Equalizer
Pioneer RG-2 dynamic processor
Pioneer PD-70 1st generation CD
Toshiba 6 head hi-fi VCR
(2) Genesis Physics 44 front speakers
(2) Genesis Physics 22 rear speakers
XLO er-4 interconnects
Monster 12 gage speaker cable

Happy hobbying!

Summary:
Well, so glad to hear that someone else has come across the Pioneer QX-8000A. Here's my experience.
The previous poster provides a lot of info about the product's features. Here's some info on how it performs. I acquired this workhorse in May 1973, when it was Pioneer's top-of-the-line quad receiver. The entire world, it seemed, was moving to quadraphonic sound and as a college student I wanted the best I could buy. The product, I believe, listed in the U.S. for $699.99 in 1973, but my brother was in Thailand at the time and I was able to buy it for $239.00 plus shipping through the military APO system. In 1999 I would guess that it would retail for about $1,600, given the inflation in the price of quality equipment.

It was paired with a variety of shoddy turntables (remember Garrard?) and a JVC quadraphonic eight-track deck, but all of my quad 8-tracks have come undone (weak splice glue, I guess) so it's gone up to the attic. I've got lots and lots of QS and particularly SQ albums, many of which were bought cheap when quad stocks were liquidated in the early 1980s. They sound great, along with the surround sound CDs.

In 1999, the product has never sounded better. I have replaced an on/off button and a power cord at my own volition, and the usual 2A fuses. Its down-and-dirty specs include 22 wpc rms x 4 channels. It contains FETs, which a dealer has said accounts for its rich sound. Deep, fat bass and fine trebles. Three years ago I bought four Polk RT12 speakers and for the first time I have heard just how damn good the thing sounds. Now I can scarcely turn the volume up beyond 11 o'clock before it gets too loud. It will not distort until the 1:30 position. I have never driven it to clip.

Quad lives on as Surround Sound! In addition to its playing flawless DAC sources I am using it as the surround sound receiver in a home theater. I play Pro Logic-encoded VHS tapes through the Sansui QS decoder and it provides a strong "phantom" center "channel" in addition to providing left/right separation of the surround channel in rear. For example, during the opening credits of Independence Day, the titles "explode" in the front and the letters individually rush by on the left or right to the rear. Doesn't give the same effect in SQ mode; I think it has something to do with the fact that Pro Logic is derived from the Sansui QS encoding. Spare L/R front outputs serve a Polk PSW 150 subwoofer for VHS playback.

I'm also using it in a DVD 5.1 setup. Here, the quality onboard decoder of a Toshiba 3109 decodes and sends 5 analog outputs. The four corners go into the discrete inputs of the QX-8000A, and the center channel goes to one channel of an NAD 314 integrated amplifier (30 wpc rms x 2) This serves a Polk CS 400 center speaker, which has the same driver configuration as the RT12s. I like the Polks because they sound great at a relatively reasonable price, although the subwoofer leaves something to be desired. The sub and the center are not used for listening to music, which otherwise would distract. Nonetheless, this is earthshaking home theater at a fraction of the cost of new equipment, and half the fun is knowing I adapted the old equipment to the new.

So what goes around comes around. Quad has returned as Surround Sound, and the old equipment still serves. I attempted to retire it last year ... bought a Denon AVR-1200. What a mistake. It sounded like a giant transistor radio and the surround function was garbage. Now I don't know what I'll do if or when this behemoth goes. It will take a lot of dough to replace this sound. I've been told that I will always be able to get it fixed, but knock on wood, it really hasn't broke down yet!

Quadraphonically yours.

Summary:
I'm submitting this largely for historical interest, but it is kind of a fun old piece of equipment. This receiver has QS, SQ, stereo, and undecoded quad outputs,
two phono inputs (one with an unequalized mic input from the front panel), two
tape loops and two auxillary inputs. The tape loops and aux ins have four-channel
I/Os. Level controls include balance for front and back, front-to-back fader, and
treble/bass for both front and back. Two headphone outputs are also present for
front and back. The QX-8000A was packaged in a walnut cabinet with an
aluminum faceplate and weights about thirty pounds. Obviously it was produced
sometime in the 1970's. Pioneer's use of their proprietary speaker connectors puts
it somewhere between 1974 and 1979. Please drop me an email if you should
happen to come across a schematic for this beast. Have fun.