Writing a warm if inevitably parti pris appreciation of Stephen Kovacevich’s nine-CD and 12-year project, producer John Fraser speaks of ‘an artist of almost self-punishing honesty and integrity’. This hits exactly the right note, for Kovacevich’s Beethoven not only bristles with a formidable physicality but shows little time for small talk or the sort of charming aside or innuendo that can sometimes endear you to less urgently committed players.

Pick any sonata and hear it in isolation and it is hard not to be awed by Kovacevich’s self-effacement, technical brio and scrupulous adherence to the score. Venture further, however, and doubts start to creep in. For all their quality, too few of these performances lift the spirits, their very ferocity mirroring itself instead of providing a renewal of speculation, depth and, above all, wonder at the heart of Beethoven’s ‘New Testament of the Keyboard’.

A similar problem beset fraught Annie Fischer in her recording of the sonatas (a project that took many years and many producers to complete) where, in seeking perfection, she somehow missed the point. Like Fischer, Kovacevich’s readings are frequently too tense to allow for the fullest sense of poise and eloquence, burning, in Walter Pater’s immortal words, ‘with a hard gem-like flame’ that can leave you feeling short-changed. Such almost palpable hypertension is, of course, central to so much of Beethoven’s vision and volatility, but so too is the relaxation of such drama and turbulence, and Kovacevich’s one-sidedness, his way of playing so close to the edge, cast a uniform colour, weight and texture on music which should surely express poetry of an infinite variety. You do not want to be reminded so often of King Arthur wresting Excalibur from its rock.

But more specifically, there is much to astonish and admire in Kovacevich’s fire-spitting launch of the series in Op 2 No 1, or in the way the Menuetto’s unsettled nature is highlighted by such a highly strung temperament. Nothing escapes his beady-eyed attention to detail or his razor-sharp brilliance and articulacy in early Beethoven. What super-charged vitality in Op 10 No 1, and how refreshing it is to hear the opening Grave of the Pathétique played so precisely in time rather than sounding like an improvised cadenza. The central Allegretto of Op 14 No 1 is just that – no mystic andante aura and alternative à la Richter, but an uncompromising realisation of Beethoven’s direction. At the same time Kovacevich can take a severe hand to music which calls for more charm (the concluding Scherzo from Op 14 No 2). He can be tight-lipped and unsmiling in Op 31 No 1 and Op 54, almost as if he had forgotten Beethoven’s delight in letting down his guard and indulging himself in so much whimsy and mischief-making.

In the Waldstein his explosive energy is brilliantly refined and controlled, even when it comes to seem remorseless in the opening Allegro con brio. He is testy rather than radiant in Les adieux’s final homecoming but more characteristically successful in the first movement storms of Op 90. But then again, blowing hot and cold, he sounds disappointingly harassed in the calm of the second movement, its relative serenity chivied and compromised. There is a dazzling sense of how quickly Beethoven with his frequent sf markings can rouse you from complacent reverie in Op 101, though here as elsewhere repeats (scrupulously observed) reaffirm what that has gone before rather than exploring and further illuminating the score.

The underlying turbulence in Op 109 surfaces with engulfing effect and the second movement Prestissimo rages with magnificent defiance. A primordial calm is achieved, too, in the final variations even when the playing stiffens into self-consciousness (the reverse of Kovacevich’s one-time mentor Dame Myra Hess, in her legendary recording). Op 106, the Hammerklavier, is a highly-charged and draining experience for both player and listener, there is a overwhelming sense of triumph at the end of Op 110, and some heart-stopping moments in the chains of trills that symbolise a spirit realm beyond earthly travail in the second movement of Op 111. Times like these (and in the Op 119 and Op 126 Bagatelles; Kovacevich has saved the best for last) help to qualify my regret for earlier performances where Kovacevich struggles to reconcile the need for the personal – if warts-and-all – charisma of a live performance with the often chill requirements of the studio; a question of Scylla and Charybdis.

An immaculate and consistent offering, then, but one that misses the heights scaled by Beethoven’s greatest interpreters. Schnabel, Kempff, Arrau, Brendel and, perhaps most of all, Solomon (who nearly completed his cycle before being struck down by illness) all offer a deeper response and a greater sense of each sonata’s individual voice. For some and, I suspect, for Kovacevich, evocations such as the Adagio from the Hammerklavier being ‘like the icy heart of some remote mountain lake’ (JWN Sullivan), demonstrate only the limitations of language, a dealing in sentimental evasion. Yet such images invariably come to mind when prompted by certain pianists, and it is they who surely reveal Beethoven in all his fullest and most evocative glory.