Quad 606 Power Amplifier

Quad 606 Power Amplifier


The Quad 606 Power Amplifier is another classic amplifier design from Quad utilising their patented current dumping technology. Essentially a current dumping circuit like the Quad 606 Power Amplifier consists of a very high quality low power class A amplifier feeding a high power low quality amplifier which is used when required.

The Quad 606 Power Amplifier was originally launched in 1987 and essentially was a new improved version of Quad's 405 amplifier with extra oomph and a whopping 140 watts per channel into 8 ohms whose sonic improvement compared to original Quad 405-2 was significant.

The Quad 606 Power Amplifier was also very popular with professional audio people as well as audiophiles possibly because of the sheer power of this amplifier coupled with Quad's reputation for producing solid well built amplifiers.

The Quad 606 Power Amplifier was discontinued in 1997 to make way for the Quad 707 power amplifier which was another current dumping design that improved slightly on the Quad 606 and was one of Hi-Fi World's recommended amplifiers at that time.

If any current owners of the Quad 606 Power Amplifier are interested, Fidele Audio offer an upgrade service which improves the original sound by replacing the class A circuits op amp (Texas Instruments TLC271) with a much a higher quality one - a Burr Brown OPA627AP and upgrading some capacitors with Black Gate (just about the best you can buy - if you can find someone who stocks them). I can certainly vouch for this upgrade as I use a Net Audio modified Quad 405-2 whose upgrade is very similar.

Quad 606 Power Amplifier Specification
Power Output: 140 watts per channel (8 ohms)
Distortion: < 0.01%
Input Sensitivity: 500mV
Input Impedence: 20Kohm
Crosstalk: -100db (100hz), -85db (1 khz) and -65db (10khz)
Hum and Noise: 105db
Voltage Rating : 220-200V AC (110-120V via simple power board modification)
Dimensions (WxHxD): 321 x 140 x238 (mm)
Weight: 12kg

This entry was posted on Friday July 28th, 2006 at 7:05 PM and is filed under Amplifiers. You can follow any responses to this entry through the RSS 2.0 feed. Comments are now closed.

35 Responses to Quad 606 Power Amplifier

Nigel from beds Says:
October 13th, 2007 at 11:40 AM

Any idea how many 606's were made please? I have a 606mk2 that has red writing on the label instead of the usual green to display the serial number. Also instead of a U ****** It starts with a number and then ends with an S. Any ideas? Thanks

Hi-fi insight Says:
October 15th, 2007 at 8:44 AM

The Quad 606 was in production from 1986 to 1997. 27,700 units were made and after serial number 21600, the amplifier underwent some major changes to improve reliability and stability which I assume is the version you have.

Asif mahmood Says:
October 27th, 2007 at 4:00 PM

i want quad power 606 what is this prise

Kim bhagat Says:
December 28th, 2007 at 1:10 PM

Hi - I have a Quad 606 power amp and am using it with a Quad 34 pre amp. I would like to change the pre amp. Any ideas?

John wyllie Says:
April 3rd, 2008 at 9:14 AM

I also have a 606 power amp and am using it with a 34 pre-amp. The 34 failed on me about 18mths ago, and I had it repaired by Quad (at a reasonable expense) and it has since failed again. I am keen to keep the power amp, but am looking to use another pre-amp. Like Kim, I would welcome any ideas you have. Many thanks.

David wilson Says:
October 26th, 2008 at 12:34 PM

I've been using a Yamaha DSPAX820 as a pre-amp that also drives B&W DM303s in the rear. The Q606 drives B&W 604s in the front. However, I get through a lot of fuses. I wonder if I need a better matched pre-amp.

Dan Says:
May 12th, 2009 at 8:21 PM

i have a quad 606 im living in nortampton its in top con im looking 4 around £250 any intrests ??

Mark richards Says:
May 25th, 2009 at 10:41 AM

Hi Dan
have you still got your 606 for sale?

Dan Says:
May 28th, 2009 at 7:35 PM

Hi Dan,

Please get in touch if you're interested in selling the 606 in the next few days......I live in MK and can collect.

Thanks, Dan

Alan Says:
July 15th, 2009 at 10:05 AM

hello. i am selling a quad 606,id like £350 for it and i live in birmingham

Declan Says:
September 18th, 2009 at 9:09 AM

I've got two 606's and feel like I'm the luckiest man alive (beautiful partner, fun job and great Hifi. Does it get any better?)! I've got the older version and the one with the new power supply. Purchased both from the same guy a few weeks ago and have the later version powering my 5-way transmission-lines at the moment. I think i've found the combination I've been looking for. These amps are amazing! Big, kudo's to the designers at Quad for this. It's got a very similar sound signature to the 303, which I love, but it's also more controlled, more transparent and seems to love difficult loads. Unlike the 303, it doesn't catch fire at random, which is an added bonus. my bryton, denon, perreaux amps have all fallen by the wayside. This is definately the amp for my ears at least.

Ian Says:
September 29th, 2009 at 3:33 AM

Me too! Ive got a 606 with 34 pre amp, great job and stunning wife of three years. Like you say does it get any better!! Just bought B&W DM 603 S3 Speakers, any one else have this combo as I haven't connected yet

Robin Says:
October 2nd, 2009 at 5:51 PM

Quad 606 and fm66 for sale,both mint with original accessories and boxes etc.
If any one interested please email ,trishavn@tesco.net.
Live in leicester.
thank you.

Peter liaw Says:
November 10th, 2009 at 2:00 PM

Any idea if I connect my Quad 606 to Sonus Faber Concerto Domus with 34 as pre amp?

Thank you

Rob hunsche Says:
November 12th, 2009 at 11:01 AM

hallo met Rob ik heb mijn quad 606 al 20 jaar. komt ook een erg goed geluid uit voorversterker quad 34 en quad fm. ik ben een gelukeg mens. de rest alles van studer en reVox ook niet kapot te krijgen nou groetjes Rob.

Gerd gorissen Says:
January 10th, 2010 at 2:47 PM

Hallo an alle hier,

lese soeben all' die Mail und kann allen nur zustimmen. Ich habe meine Quad 606 + Quad 34 + Quad Tuner FM4 seit 1985 und damit super zufrieden und würde sie gegen nichts tauschen. Meine Boxen Jamaha NS1000 Monitor bringen das ganze zu einem guten Klangergebnis.

Mit freundlichen Grüßen

Dragan Says:
February 9th, 2010 at 10:07 AM

I am interested in quad fm66 - anybody offering one?

Ste cobbold Says:
February 23rd, 2010 at 10:12 AM

Hi any one selling a 606 mk2 and a 66

Cody gendreau Says:
February 24th, 2010 at 2:25 AM

quad amp 606 for sale great condition 300$
cody gendreau

Andy Says:
March 5th, 2010 at 12:17 AM

If you're still looking for a FM66, please get in touch

Glyn overbury Says:
March 29th, 2010 at 12:52 PM

I am in Western Australia and I need to replace my now defunct Denon with a decent amp. I have an old Quad 34 and I am looking for a 405 or 606 to drive my ESLs.
Any takers?

Amber Says:
April 15th, 2010 at 8:33 PM

Anyone selling quad 606 in UK please get in touch. cheers.

Craig Says:
April 30th, 2010 at 9:30 PM

I have a Quad 606 with FM66 in v. good condition plus Ruark Broadsword speakers and top quality interconnects. Located in St Albans, UK. Open to offers.

Fergus Says:
May 12th, 2010 at 11:41 AM

I'm interested in buying a 606 either Mk1 or Mk2 - please get in contact if you're selling (I'm London based).


Arup Says:
August 14th, 2010 at 4:21 PM

Owner of 34, 306 & 606-II. My 606-II have the serial no starting with " Q " and its a late 26,8XX unit sporting a toroidal transformer made by Airlink Transformers UK & Aerovox UK (15,000uF caps x 4). Overall, I've been extremely pleased with my purchase of the 306 (1987) and 606-II (1995). The circuits are identical with much more oomph in the 606-II. Never had a snag (touch wood!!) and Quad gear is ultra reliable - bullet-proof. Easy to repair as all parts are available.

IMO - I wouldn't play around with the opamp TLC271 as it directly affects the turn-on thump & turn-off with DC problems that can seriously affect your precious loudspeakers. Also, changing the opamp eats away the typical lovely laidback, easy going composure of the amp together with the tonal fullness. Have tried all these things and finally reverted to the amp with stock parts albeit 1 blackgate cap at a very critical area of the circuit. Yes, I have accepted the amp the way it is. A "quad is a quad", it ain't gonna be a krell & seriously it shouldn't be transformed to a krell either. If krell is what one wants, 'en leave the quad alone & get a krell!

The 34 preamp - though offer lots of lovely tone shaping facilities nevertheless, is poor in transparency, lethargic, bloated, and just a downright ordinary preamp that when mated to Quad poweramps just drags the overall performance down. Get the preamp (34, 66, 77, 99) out of the way, fit a nice clean passive (either L-pad or shunt type with a great pot & great resistors) and watch the poweramp just take off in a totally new direction... Do it and you'll be rewarded many, many times! Quad poweramps are great on their own.... Always a keeper & I'll never sell mine.


Nandan Says:
September 6th, 2010 at 10:20 AM

I'm interested in buying a Quad 66 pre amp.
im living in Kerala,S.India

Senarath rajapakse Says:
September 21st, 2010 at 9:53 AM

My QUAD 606 power amp. remote controller badly dammaged.If anyone has spare one, please let me know. I am living in Sri Lanka

Daniel Says:
October 27th, 2010 at 2:57 PM

Hi I have a quad 606, 44 pre, 405-2 power amp and the mighty Gradient sub base units all for sale as a package or to sell seperately ! ! Please ring 01233 624441 and ask for Daniel

Chai ong Says:
January 23rd, 2011 at 5:39 AM

hi Daniel,

Are ur quad 606 still available? what country are u in?

Samson amor Says:
February 10th, 2011 at 6:41 AM

hi gud day..
is there any available of quad 606, BRAND NEW and how much?

Dratit Says:
February 12th, 2011 at 11:08 PM

I have had years of pleasure from the QUAD 606 I have but last week the preamp remote stopped working.Locally no one seems to know how to repair it. There is much muttering about the uniquness of its'chip.
can Quad repare it? where?
Any help would be much appreciated.

Matthew whyte Says:
August 19th, 2011 at 10:27 AM


Jonny Says:
March 18th, 2013 at 8:50 AM

66/606 for sale with remote console, 606 upgraded during service, no boxes, pristine condition, used for less than 300 hours, one owner, bought new circa 1990, offers please to jonnydeal@ymail.com

Niya audiophile Says:
August 2nd, 2014 at 2:07 AM

I have a 34 and 606 partner since 1993 they have never been upgraded and still sound as good as new, had a little clean up on the inside of the 606 today, sounds great

Soumyajit basu Says:
September 27th, 2016 at 6:52 AM

I am interested to Buy Quad 606 MKII with matching pre- amp. I am in India. If is available plz call me at 9831364386.

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