Strengths: Power enough for smy KEF reference speakers , musical, good staging.

Weaknesses: bass resolution, high temperature. Very bad support. only for this, avoid buying unison produt.

Soundstaging improved over my SS amp. musical but harsh sound with EHx tube. Huge improvement when using telefunken 802s (12au7): detailed mid-range, highs are sweet and smooth. Drawback : bad, bad support.My dealer never get transfo output replacement after 8 months phone calls and mails.So I got S6 demo replacing my S6 but with no remote. The dealer ordered a remote since july 2004. Until now nothing came from Unison. If you buy an Unison product pray to not needing their support at all.

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Jolida

musical,easy to find tubes, fantastic on voices and jazz, reliable, low power consumption, remote control, passes without problem the WAF (women's acceptance factor !)

none

It's been now 9 month that I have purchased my S6 Unison Reaserch of which I am very satisfied. Great warm sound, very musical (no harshness at all),very good reserve of energy and very detailed as well. This unit deserves good smooth source, interconnect and power cord. If wished, bass can easily be increased by replacing the poor Electro Harmonix by Ei 6CA7/EL34 big bottle or Sveltana's and good 5814. An outstanding choice for voices and jazz. I highly recommend it.

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Audiomat Prelude Ref, UR simply four, Brinkmann, Mc Intosh.

Power enough for speakers in general, musical, good staging, never feel harsh in high mid at all

Poor bass resolution, dynamic lose a bit.......sorry I compared it with VAC models. So troublesome to setup, plug tubes, caring temperature, etc

Just sold the amplifier and feel a little bit regret when I am reviewing with the buyer. Staging is excellent where I can feel the positioning of the vocal and instruement. Very musical as I never feel on harsh sound. Very punchy when pairing with my ProAc T2000s speaker on stands. However, I do have a complain, the bass, it is not as clear as solidstate amp produces. Resolution is losing a bit. Otherwise, it is a fairy good choice for tube guys to play.....S6 is UR int amp flagship in my heart......coz I dont really like the sound from 845, tube model used by their real flagship S845

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Opera Ref 6.6, UR S845, VAC (forgot model number, but using 4 EL34s, integrated amp)

Beautifull midrange.For this price EVERYTHING!

Ask it to marklevinson and krell owners.

This was my first experience whit tube Ampliefiers.I will never again go back to transistors again.For the price it is a exellent product.A friend of me ho listend to the Unisonresearch S 6 at my home sold his pre power combination Marklevinson (very expensief model 7x) he was depresd how good for that money the S 6 is.Strongly recomended!

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Before all transistors.

Warn & sweet vocal voice but cannot catch deep bass

Too heavy, power consumption

It is a delicate amp and the state of art. My loudspeakers are Harbeth M''40. They are really good in concerto and soprano''s aria. But it''s a lttle loose at heavy metal. I think that it does not matter. Because I turn the sound switch over 1200.

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none

Musical, sweet rich and "full" sound. Excels with female vocals, jazz, classical and acoustic material. Can rock too. Looks great and well made. Can drive moderate sensitivity speakers easily.

Standard input tubes (Sylvania 12AU7) makes bass a bit slow and overly warm/"loose", Runs hot, energy consumption (?), heavy to lift! (25 kg)

A really nice sounding amp...musical and not tiring like some amps. Really good with simpler acoustic classical, jazz, folk amd female vocals. Plays orchestral pieces and rock pretty well but lacks solid state slam (as expected) but makes up everywhere else...lovely smooth sound, very good soundstage, "presence", conveys nuances and rhythm of music well. In my humble opinion that is. Not as transparent and "there" as with a good single ended triode amp and doesn't have razor sharp top & bottom end like moderately priced solid state gear (A blessing I'm sure, I don't think I'm missing too much with this tube gear though)
It runs pretty warm, especially at low volumes (as expected for class A and single ended operation) so must draw reasonable amount of power to achieve power output. cooler if ran at higher volume or with rock.
A bit of experimenting revealled the input tubes contribute significantly to its perceived weaknesses : the Sylvania 12AU7's impart an overly warm, slow and overblown bass. A change to NOS Mullard CV4003 or Radiotechnique 12AU7WA especially improved things no end in redressing the balance. Lovely mids a bonus too, better top and bottom end control and speed. Bass is more controlled/more speed imparted with the new tubes. Not had time to try Svetlana EL34.
The amp looks cool, the tube cage is brilliant: looks cool and keeps the kiddies hands & finger out! Remote control is novel (works on radiowaves not IR) but works all around the house. Amp looks well made and is hefty to lift. Drives my concerto's pretty well...dont need to crank the volume to more than 1030 position before its too loud and doesn't seem to stuggle/loose control at this volume. No reliability problems so far in 6 months or so.
I am very happy with the sound, particularly with the "new" "old" 12AU7WA's in place. A happy tube convert.
Rating? Depends... I dont think mega dollar gear necessarily gaurantees enjoyment, I also haven't listened to everything out there but have a fair idea over the years, so for the money (1600 GBP)..

Associated equipment:
Anthem CD 1 (Mullard CV2493 in output stage rather than stock Sovtek 6922))
Sonus faber concerto's on fixed ironwood stands
Nordost blue heaven interconnects and speaker cables (2 runs, biwired)

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Audiolab 8000S
Anthem Pre1 and amp1
Krell 300i

Brings heart and soul to your music, very good soundstaging,

None

This is the ultimate 'foot-tapping' amp! Musical all the way!

After extensive listening I decided on this model, and I haven't been disappointed yet! It has improved my listening pleasure so much. Both at loud and soft volume you are drawn into the music. The level of detail is enormous, without being too detailed as an analytical amplifier may do. Bass is supposedly disappointing with tube amplifiers, but it is enough for me, and well defined (and I haven't mass-loaded my speakers -yet-).

Unison even provides a remote control for the volume, although it is very basic. Prices are a bit lower in the Netherlands, but even for the US price this is a very serious contender if you're amp is up for renewal!

My system:
Arcan FMJ 23 CD
Unison Research S6
Ruark Prologue R speakers
MIT T2 interconnect
Linn K20 speaker cable
(temporary, once the system is burnt in I will start auditioning interconnects and speaker cables)

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Tested agains Audio Analogue, Cyrus, Rotel, Unison SR1,