Listening to the Koras, it’s not hard to identify their tube-like and Class A characteristics, obvious in the rich tonal colours, dimensionality, musical flow and intimacy. Their sound is built around temporal and harmonic integrity, and whilst not short of dynamic impact and contrast, it’s longer on subtlety and nuance. At 300Watts/Channel the S-400 II is significantly more powerful – and sounds it. The Koras lack the sheer substance and dynamic heft of the VTL, it’s towering dynamic crescendos and unburstable sense of energy. But the big tube amp is about more than just dynamic range and impact. It’s overall musical coherence, stability and control (the product of its massive and heavily regulated power supply) contributes the planted quality behind its sense of purpose and musical momentum, its effortless, wide-range dynamic agility and expansive, beautifully defined sense of acoustic space. Big and bold, the VTL is also an incredibly safe pair of musical hands, capable of dealing with anything the recording throws at it, without confusion or congestion, compression or collapse.
Nor can the Koras match the sheer clarity, resolution, integration and temporal organisation of the M1.1. The CH amp excels at locating the note in time and space, it’s centre of energy and the gap and step in pitch between one note and the next. Its micro-dynamic resolution and immediacy are both excellent, improving still further if you use the Swiss amps in a bi-amped rig. It would be easy (and lazy) to simply suggest that the Koras sit somewhere between the two and leave it at that. But the reality is rather different. This isn’t a continuum: it’s more of a triangle, its centre ground dominated by the human agency in the music, the relative performance of the different amplifiers defined by their relation to it.
Many amps, especially tube-based amps, make Ella sound beautiful. With their natural warmth and rich harmonics, the Koras do that too – but they do a lot more besides. Play ‘Good Morning Heartache’ from Clap Hands… (Analogue Productions CVRJ 4053 SA) and her vocal control and phrasing are as majestic as ever, but the intimacy and shape that the Koras bring to the vocal make it soulful and heartfelt too. There’s a real depth to the feeling behind the vocal. This is more than just singing for singing’s sake. Too many systems gloss over that depth, turning Ella into more of a vocal show-pony than a serious artist. It sounds ‘nice’ (which might be why you hear Ella’s voice so often at audio shows) but it misses the point: a point the Kora’s make forcefully but with finesse. And if you think the presentation with Ella is impressive, just wait ‘til you hear Billie…
Not as focussed, dimensionally defined or immediate as with the CH amp, the Koras actually communicate the sense of the song, the presence and input or intentions of the singer more directly and convincingly. It’s partly the natural mid-band tonality and harmonics that are certainly on the CSA-1200s’ super-powers list. But it’s also about the diction and timing. The Koras might lack the temporal and dynamic precision of the M1.1(s), but they offer instead a more relaxed grasp on the time-domain that keeps everything just where it should be (certainly in musically terms) without being quite as obvious about it. Now ‘obvious’ is not a word I’d normally find myself using in conjunction with the M1.1, but the calm, unflustered competence and fluid articulation of the Kora monos manage to achieve just that.
