Leben Stereo Hi-Fi Company is very close to my heart, perhaps as no other manufacturer. Maybe I could also add Ancient Audio to the same group. The Leben CS-300 amplifier simply amazed me with how much music can be squeezed out of such a tiny box. But it turned out that there was space for improvement. Version XS [Custom Version], upgraded with V-Cap capacitors, custom made for me by Mr. Taku, Leben owner and designer, showed that the CS-300 was just a starting point. Since then I reviewed most of their products and each one was at least very good. I did not like all of them as much as I did the CS-300, but they were really OK. That is, until I heard the CS-660P power amplifier and I fell in love with it. Its sound was simply captivating and charmed the listener in a way that I had never heard before, even with very expensive designs. So when I learned that Mr. Taku was working on a new, more powerful version of the power amplifier, it really stirred my curiosity.
CS-1000P, because that’s what we’re talking about, was designed for one simple reason: the Russian Tung-Sol company launched some time ago a new model of their tube, a stronger version of the KT88 beam tetrode, called the KT120. Leben is not the first company to use it; Octave and Ayon Audio already did. The new power amp from Leben is special in that apart from the KT120s, it can alternatively use such tubes as KT88 and KT66, 6550A/C, 350B, EL34, and KT77. For this review I received a version with the KT120s and I do not know how the amplifier behaves with other tubes. Regardless of how it sounds with them, I must say right away that the new amplifier looks absolutely brilliant and no matter how much I liked the CS-660P, the CS-1000P beats it hands down in this respect.

SOUND

Recordings used during auditions (selection):

• Blade Runner, soundtrack, muz. Vangelis, Universal, UICY-1401/3, Special Edition 3 x CD (1982/1991/2007).
• For Ever Fortune. Scottish Music In The 18th Century, Les Musiciens de Saint-Julien, Robert Getchell, Alpha, 531, CD (2012).
• Paganini for two, Gil Shaham, Göran Söllscher, Deutsche Grammophon/JVC, 480 246-5, XRCD24 (1993/2009).
• Chet Baker, Chet Baker Sings and Plays, Pacific Jazz/EMI Music Japan, TOCJ-90028, HQCD (1958/2008).
• Chopin, 4 Scherzi, Ivo Pogorelich, Deutsche Grammophon, 439 947-2, CD (1998).
• Diorama, The art of creating confusing Spirits, Accession Records, EFA 23450-2, CD (2004).
• e.s.t. Esbjörn Svenson Trio, 301, ACT Music + Vision, ACT 9029-2, CD (2012).
• Ella Fitzgerald & Louis Armstrong, Ella and Louis, Verve/Lasting Impression Music, LIM UHD 045, UltraHD CD (2010).
• Exodus, Supernova, Polskie Nagrania/Metal Mind Prodictions, MMP CD DG 0405, CD (1992/2006).
• Glen Gould, Bach: The Art Of The Fugue, Sony Music/Sony Classical, SMK 52 595, The Glen Gould Edition, SBM CD (1997).
• Handel, Arias for Cuzzoni, Simone Kermes, Lautten Compagney Berlin, dyr. Wolfgang Katschner, Berlin Classic, 0016422BC, CD (2009).
• Jean Michel Jarre, Magnetic Fields, Epic/Sony Music, 488138 2, CD (1981/1997).
• Jean Michel Jarre, Téo&Téa, Aero Production/Warner Music France, 699766, CD+DVD (2007).
• Lisa Gerrard, The Silver Tree, 4AD/Sonic Records, SON212, CD (2006).
• Nosowska, 8, Supersam Music, SM 01, CD (2011).
• Novika, Tricks of life, Kayax 013, CD (2006).
• Stereo Sound Reference Records, A Day at Jazz Spot ‘Basie’. Selected by Shoi „Swifty” Sugawara, Sony Music Direct (Japan)/Stereo Sound, SSRR6-7, 2 x SACD/CD (2011).
• Vangelis, Spiral, RCA Records/BMG Japan, BVCM-34430, K2, SHM-CD (2011).

Japanese versions of the recordings available from

Leben CS-1000P is the best, so far, amplifier from Leben. Not “somewhat”, nor “slightly”, but simply the best. Period. It belongs to a group of devices that force different types of activities on the listener – from searching through his or her record collection just to hear this or that album, often long forgotten, to generating new album purchases, etc. In my case I took the “ebay” road, straight after hearing the new reference album from the “Stereo Sound” magazine, titled A Day at Jazz Spot ‘Basie’. Selected by Shoi “Swifty” Sugawara, featuring – obviously – Count Basie but also Armstrong, Monk, Buddy Rich, Harry James, etc.
The sound of the Leben is exciting, electrifying and moving. This is not an ideal sound, in the sense of “absolute”, because I found with model CS-660P a certain sound characteristic that is not present here, but nevertheless it is a clear step forward in comparison to the “six-hundred-and-sixty”, which I so greatly enjoyed.
The ‘1000’ sounds more detailed, clearer and more dynamic than the ‘660’. The lower bass and the upper treble have been slightly emphasized, which make the sound seem slightly contoured. And it kind of is. This adds, however, some momentum (bass) and breath (treble) to the recordings. It conveys a very resolved, selective, well-differentiated message. And beautifully arranged at that.

What is most important, however, is that the reviewed amplifier delivers a whole, complete message. Although my above, initial impressions concerning the Leben’s sonics were clear for me from the outset, it is not these “guts”, if I may say so, that define the unit. We simply get here a finished sound, which can of course be improved here and there, but these will not really be “improvements” as much as “redefining”. I can see for example that swapping the KT120s tubes for some NOS of another type will bring a significant change of the sonic character. The amplifier seems to provide a very solid base for this type of tube shuffling, clearly showing the tube characteristics, instead of how well it “resonates” with the amplifier.
With the stock tubes, and let me remind you that the Leben has been designed specifically for the new KT120s, the sound is extremely dynamic. I could not detect any power restrictions, no compression whatsoever, no matter how loud I cranked it up. This, I think, was one of the design objectives of Mr. Taku, the designer and owner of Leben.
The dynamics and the tonal balance of the device can be, to some extent, regulated. We have two switches for that – the “triode / pentode” mode switch and the speaker impedance selector. The former shows the musical material either in a more intimate or more dynamic way; the latter does two things: it changes the sound timbre and its “focus”. When set to “4 Ω” the sound is warmer and much more withdrawn into the scene. The vocals are more integrated into the background. In the “8 Ω” position the sound is clearer and the vocals are nearer us. Various combinations of these two switches provide different effects. For me the Leben sounded best in the “triode” and “8 Ω” positions. With other speakers (than my Harbeths M40.1) the effect may be different.

Leben CS-1000P delivers sound with great panache. Recordings with deep soundstage sound absolutely beautiful – the music to Blade Runner or the album 301 by e.s.t. group (amazing music!) sounded vivid with accurate transients, including long decays. Space, excellent layering and a great interaction of all components were just a prelude to what was most important: excellent energy transfer.
This is a characteristic described by various terms and referred to on different occasions, and yet one that is immediately, almost palpably noticeable during auditions. It is a sense of the instrument’s or the vocalist’s presence in the room, here and now, in front of us. It is often referred to by the phrase “tangible sound”, but it is something more than that. It is not just the ability to extract a well-defined sound source, and to present it close enough to the listener, but also the palpable strength of the sound, the power that moves everything.
In consequence, with the Leben we do not pay special attention to rhythm, to sound focusing, because they are simply outstanding; instead, we can pay attention to their differentiation between various recordings, such as going from an album by Ivo Pogorelich playing Chopin to Glenn Gould playing Bach. Different playing techniques, a completely different way of recording – the Leben differentiates all this in a unique way. Interestingly, it does not discredit any of these performances – neither the would-be winner of the 1980 Chopin Competition (just to remind you: he was eliminated by the verdict of the jury chaired by Martha Argerich) with his very dynamic, clear articulation, fast attack of a large instrument in a large hall, nor the eccentric Canadian, a fanatic of new recording techniques, a perfectionist with his very intimate way of playing, and his instrument with a small amount of “air” around it.

For example, the 8-watt SET Triode TRV-3000SER clearly favored the album by Gould, probably not quite coping with conveying the full impetus of the Pogorelich’s recording.
This is just a small example of how well the amplifier handles its power – not just to show off a low, powerful bass, as indeed it does – but in order to “manage” it by drawing a powerful scene, dynamics shading, etc.

But as I already said, this is not a ‘perfect’ amplifier. I remember very well why the CS-660P model from the same manufacturer impressed me so much – its sound was also “finished”, “complete”, but it was due to its warm lower midrange and upper bass. It was an “intimate” sound, penetrating us inside out. Incredibly romantic, while being sufficiently precise. We do not find it here. The CS-1000P designer evidently moved on, clearing the range of any coloration (which is what the “romance” really was), evoking in us a storm of emotions by convincing us that we deal with something real. Gone is the small “cheat” that Mr. Taku used in the CS-660P. And I miss it a little.
As I wrote in my editorial to this issue of “High Fidelity” (HERE), a fundamental feature of a good device (system) is whether it is able to convey emotions captured in the recording. This can be achieved in many ways, but the one that defined the sound of the previous top Leben amplifier was extremely attractive. The CS-1000P is better in every way, and does, eventually, the same, but I find myself yearning for the ‘660’ “school”.
The ‘1000’ powerful bass may also present a slight problem. It is not so well controlled, as suggested by the amp’s output power; while not really bad, the lowest bass sometimes decays longer than it should – and is quite substantial. In smaller listening rooms, where the sound has no space to “expand”, it might prove to be a step too far.
Besides that, I have no more questions. I reviewed the unit with stock tubes, and yet there are lots of different types of the 6922 available; likewise, the options of swapping the output tubes are plenty. With the built-in bias current meter such swapping is made simple – the ‘660’ was, for me, not quite straightforward in this regard. The CS-1000P creates an excellent framework onto which you can “hang” anything: tubes, fuses, feet, whatever else you fancy, and the amplifier will let them sing with their own “voice”. It’s a really great amp; the best Leben device I know. And while adding just a few characteristics of the CS-660P would transfer it into the area of top high-end, occupied by my Soulution 710, or the best SET amps, I do understand the designer’s choices and I am very impressed with their result. Not to mention the fact that the amplifier is simply beautiful. The transformer cover reads: “Your lifelong partner, to live with music.” I fully agree!

The amplifier receives the RED FINGERPRINT award.

Review methodology
The amplifier was placed on the Audio Pro Bono anti-vibration platform with a new bearing suspension and feet. The platform sat on the wooden shelf of the Base IV Custom Version rack.
The CD Player was hooked by the Acrolink Mexcel 7N-A6300 RCA interconnects. The amplifier was powered by the Harmonix X-DC350M2R Improved-Version cable (test HERE ).
The auditions were A-B comparisons with A and B known. In addition to my reference amplifier, I compared the Leben to the Triode TRV- A300SER and to the SPEC RSA-V1. Music sample were 2 minutes long.¶The CS-1000P is nominally a power amplifier. However, since it features an input potentiometer, it can be used as an integrated amplifier.
Contrary to widespread opinion, such a configuration rarely makes the grade. In this case, as with the CS-660P, it is one of the better options. The amplifier can be driven by a preamp, but the best resolution, while maintaining weight, we get by hooking up the player directly. Or yet another way – using a CD player with a built-in preamplifier, like my Lektor. It proved an excellent combination.

DESIGN

CS-1000P is a power amplifier with adjustable input sensitivity. However, it can be used as an integrated amplifier, with the volume controlled by a small knob (41-step attenuator) on the front panel.
This is a tube amp with a solid state rectifier (CS-660P in a tube), with two Electro-Harmonix 6999 tubes in the input, and two General Electric 6CG7 in single-ended class A, driving the output stage. The output stage operates in class AB, push-pull mode. It uses the latest “invention”, the KT120 beam tetrodes, being a more powerful version of the KT88s. Recently, they are very fashionable – used by such companies as Ayon Audio, Octave, and others. Alternatively, you can use the following tubes: KT88, KT66, 6550A/C, 350B, EL34, and KT77.
The overall looks of the amplifier is nearly identical to the CS-660P, however, the paint finish is darker (and prettier). The design is classic – with tubes in the front and transformers behind them. The output transformers and the power supply choke are shielded under a single enclosure, with the power transformer next to them, off the shield. In front of the latter we see a nice indicator (mA meter), showing the output tubes cathode current. The meter is made by “an established Japanese company,” as we read in the brochure. In front of the meter we have a selector knob, selecting which tube bias current we adjust. And finally, four multi-turn potentiometers. The inclined front panel sports a mechanical power switch and an illuminated label that says "A Motion Sound". On the back panel we have nice speaker terminals, and between them a selector, choosing output transformers taps – for 4, 6, 8, and 16 Ω. It’s really nice. To the one side of the terminals there are exceptionally solid RCA inputs from Canary, to the other a large toggle switch, to choose the output tubes operating mode. There may operate in a normal mode, as tetrodes (position “pentode”) or with their screen grids directly connected to the plates, in a triode mode (“triode” position). On the left side there is mains socket and fuse.
The amplifier stands on solid, brass feet with microporous rubber.
¶The interior looks unusual, because it is a study in simplicity. Clearly, very clearly Mr. Taku chose to eliminate a lot of components from the main and auxiliary circuits, and he went for maximum simplicity. You really need extensive experience for it “to work”!
The signal from the input goes via “Million” model cables from the Japanese company Kyowa Ltd. to the Alps “Blue Velvet” potentiometer on the front panel. The potentiometer chassis is grounded, with signal mass soldered to one of the screws. From the potentiometer the signal goes to the input stage tubes, operating in SRPP circuit, with one half of tube (triode) working as a load instead of a passive circuit with a resistor and a capacitor. We see tantalum resistors employed here. The signal then goes to driver tubes, coupled to the output tubes with polypropylene Mundorf capacitors. They are cathode, not anode, coupled. All resistors are of precision metal grade type. All tube sockets come from the Japanese Omron. As a matter of fact, most components are Japan made.
The power supply design is interesting. No filament current is rectified – we have separate transformer windings for the input tubes filaments and for each channel output tubes filaments. Bias current is rectified and filtered. Anode power supply is common to all the tubes – it is a series of pi-type filters (textbook design), with a choke and resistors.