First of all, this power amp. is pretty sensitive (0.5V input for the rated output). So if you couple it with some high gain, high votage output preamp., you have no turning space on the gain/volume control. Of course, it mate well with QUAD own 34/44/66 control unit, but I have read it somewhere on rec.audio.high-end that it has good synergy with Threshold FET-9/10 preamp. I have also heard that the a 707 (a revised 606 with the new QUAD bus connector) or a 606 Mk II sounds better than the original 606 but I have never been able to make the comparison.
This is a power amp. for a person who wants to listen to music rather than who wants to tweak with his/her equipment. It is by no mean a very high-end power amp., but boy, does it reproduce music! This is a power amp. which I always want to go back to. Connected with QUAD ESL-63 they make you forget about the equipment. They just make the music flow through your room to you smoothly and nicely IMHO. You can also pair up the 606 with any incarnation of LS 3/5As. I have tried a pair of Spendor 3/5As with good results. These combos sound their best with classical chamber musics, Jazz, any vocal musics, and instrumental musics; the power amp. sounds a little bit, shall I say, congest with big orchestral musics like the climaxes from any Bruckner symphonies. But, don't get me wrong, it won't make you feel uncomfortable with orchestral msuics. It's just that 606 is not in its best with them. The high and low are not very extend, but for some reasons, I don't find this disturbing once my favorite music is playing. I guess I always have a soft spot in my heart for QUAD stuffs (I own QUAD 33, 303, 34, FM-4, 606, ESL-63s currently. Anyone has excellent condition QUAD FM-3 and CD67 for sale? :-)). I never listen to any techno, rave, heavy metal, hard rock... etc. and I can't say if 606 would fit those music genres.

Anyhow, if you believe in audio component should only be a tool to bridge the gap between the music recordings and the listeners, and you're not very enthusiastic about playing around with equipments, this is the power amp. for you. I will give it four stars.

p.s.: I think I'm the first one who post a review on QUAD 606 here (the person who openned up this category did not post a review). Hope somebody could share their thoughts on 606 here later on.

I bought a set of Quad 34/606 for my parents in 1989 (I guess?) when I was still living with them. The first good thing is the set has never broken down on us. Usage has been and is still extremely frequent as all our entertainment (i.e. TV, CD, Cassette, VCR, VCD, etc.) is channeled through it. We use a pair of KEF 105 II, which has also been trouble free for 10 years.
I have since moved out to my own place. Frankly, I was not convinced at the beginning that Quad is as good an amplifier any other. My purchase in 1989 was justified more by the reliability than the sound quality of the equipment. As a hi-fi bug, when I moved out in 1990 (from my parent's place) I went on to search for the so-called 'hi-fi nirvana' and during those times (1990/97) I have owned amplifiers such as Musical Fidelity, Audiolab, Audio Innovations, Copland and Exposure (the best of the lot). I am not saying that these equipment are not good but somehow Quad keep drawing me back with its sense of musicality and its most natural tonal balance. Yes, I have heard better systems but they cost silly money! Quad to me offer the best balance of reliability / sound / money to music lovers.

Therefore, my return to Quad in 1997 was somehow predicted. I did not want to miss the chance to buy a Quad 66/606II as I knew then that the present range is going to be phased out. The ownership change in Quad may not guarantee the same sound and I do not want to buy something that I am not familiar with. After my purchase, I have compared my 66/606II with my parent's 34/606 and found that there is no major difference between the two. As far as I can recall, the newer 66/606II offers better clarity and definition, which allow the listener to follow the line(s) of music a little bit better. As such, the imaging improves. This is as far as I can remember of the little difference between the two … by no means material given that 34/606 is close to 10 years older than my latest purchase! This goes to show that any old 606 is a good buy provided the transformer is in good working order and does not hum.

For a Quad owner, it is also good to know that Quad equipment is used in recording studios worldwide. I believe that in order to get closest to 'studio sound'; one needs to own 'studio standard' equipment. It is no use owning high-resolution equipment, which at the end of the day put 90% of your CDs/LPs into the dustbin. I have seen many hi-fi enthusiasts lost sight of the simple purpose of a hi-fi system - which is to convey as exactly as possible the original music - in their quests for the 'perfect sound'. These are the same people who take more pleasure in owning expensive equipment but not the software. It does not take a genius to know at this point that there is no 'perfect sound' in the hi-fi world as they are only recorded music. Different recording techniques/studios/equipment will yield different results playing through different systems. The permutations are aplenty and to say one system is superior to the other could be in many cases quite misleading. My believe is to keep my hi-fi system 'pure and simple' based on tested principles and this has so far enable me to enjoy a wide range of music.

My system now comprises Micromega 2.1/Duo BS, Quad 66/606II and Rogers Studio 2a (the 'washing machine' size studio monitors). The sound is devoid of sibilance; and the tonal balance is neutral and free from glare. The system is a good antidote to the CD-format which has proven to be 'harsh, clinical and bright' in many instances. I still come across CDs' that sound harsh/bright. Fortunately, the tone control of my preamp (Quad 66) has been effective in toning this down to a bearable level. This is yet another praise to Quad for coming up with such an effective tone control. Overall, I would say that I am very happy owning a Quad set and therefore, award five stars to each of the equipment (i.e. Quad 66 and 606II); more as a combination than as separates. And I am not so sure in this crazy world of hi-fi today; there is anyone out there who is happy owning the same equipment after ten years!

Warm liquid sound, strong tight bass, produces beautiful music at any volume with any music type.

Very revealing of source flaws (what goes in - must come out!!!) - Quite sensitive input, may not match well with Pre-Amps that have high output voltages.

After many years of using my 405, I bought the Adcom 555 - it worked well with my Quad ESL-57's - suddenly they had bass... the extra current and sheer oomph provided by the 555 brought them alive, and made the sound from midrange down far fuller.

Unfortunately, it was not as complimentary in the mid-high, vocal range, where the system lost some of its sweetness...

I ended up selling the Adcom 555 and reverting to the 405 for a couple of years while considering my options, moving to a different country and going through general domestic upheaval.

In the meantime my pre-amplification improved markedly from a Marantz audiophile pre-amp to a Lexicon DC-1... this caused a massive improvement in sound - I also went from the ESL-57 to the ESL-63 (more of a sidestep than improvement... different strengths)

Finally I revisited the power amp issue and decided that the best way to get the mid-bass and bass control and fullness that the Adcom provided while maintaining the sheer musicality of the 405 was to get another Quad amp of later vintage and greater power.... the 606.

BINGO - the differences were subtle but immediately evident - we listen to a lot of vocal, jazz, pop, as well as orchestral, and the system also gets used for home-theatre...

We immediately started hearing details in recordings that we had not noticed before, there was more detail, and a lower noise floor - the black silence between bits of music was just so much "blacker"

The overall sound was more full "lusher", while being more detailed, and the bass was noticeably tighter, and more "with it".

Highly reccomended!

I have also experimented a little with varying the preamp, inputs etc...

This amp easily reveals flaws and improvements in the chain before and after it. It is one of those rare components that improves as the rest of the system improves

Similar Products Used:

Quad 303, Quad 405-II, Adcom 555, Revox B251, NAD 3020...

High Price/Performance; Good Looking Chassis

Have been using Quad 606 for 3 yrs.+. now it's connecting to the following equipment:

CD Aura 10D
Decoder Audio Alchamy DDE3.0
Pre-amp CJ-PV10a
Speaker ProAc Tablelette50 Sign.

Seldom switch off the main power and works fine so far. Before using CJ-PV10a, I had been using my NAD 302 as pre-amp. Of course, before purchasing 606, I had used NAD 302 for a yr., but found this integrated amp. lacking capacity to drive my previous speaker Roger Studio 3 (w/ sensitivity 85db). Using a tube pre-amp instead of a Quad one for the reason of expecting warmer sound (maybe SS pre-amp will achieve more detail).

Bass control for 606 towards Tablelette 50s is brilliant and dynamic. High freq. range is smooth and natural. When playing vocal, if voice can be sweeter, then it would be more attractive. Anyway, at this price range (at around USD1000), I gave highest rating for value. Maybe, it's because of the characteristic of my speaker. Can anybody comments on this point?

Build quality, control, bass, clarity, placement of instruments, space, voices; EVERYTHING!

Gives a little "bnk" to the speakers when switched on.

When I bought B&W loudspeakers (Matrix 804), I was very pleased with the combination with my previous amp; a Nakamichi integrated amp (Amplifier 2, 2x50 Watts). But my system would not want to sound exactly like my fathers one, who has a Quad-system with B&W Matrix 2-speakers.

Until I bought the 606 (combined with a Harman Kardan Citation 21 pre-amplifier). What a difference! This amp really controls the speakers, gives better bass, clarity, control and spacing. Wow! Don't believe stories that there are no bad amps; this might be little true; but there are reasonable, good and excellent amps. This Quad is excellent, and the difference with others is significant enough to be noticed.

A story in a recent Dutch audiomagazine told about a listening session with audio-enthusiasts and experts. Very expensive equipment was used; electrostats, Mark Levinson amps etc; with a total value of over USD 100,000. The experts were pleased, but had all kinds of remarks and notes. After app. 1 hour, just for fun, the normal home-installation of the person where the session was held, was listened to. This was a Quad-system with B&W-loudspeakers. This system managed to entertain the listeners better, and they therefore liked it better than the very expensive upper-end system.....

Quad amps are also used all around the world in recording studios etc., so what more needs to be said? The name Quad maybe has an image, but this is certainly deserved!