The conventional mingles with the unconventional. Christian Gansch represents the conventional. He is a well schooled conductor and helpful partner with a good understanding of idiom and a keen ear for orchestral layout – violins are separated – but, interpretatively, he has nothing special to say about the music.

The unconventional comes from Mikhail Pletnev. His entry in the opening movement of No 1 occasions the first surprise. He slows the tempo right down, perhaps to underline the introduction of a new theme, one that also reappears unexpectedly, if slightly disguised, in the slow movement. More contentious are the deviations from the text, not simply the firework of a glissando into the recapitulation. Many pianists alter Beethoven’s semiquaver run here, but they don’t reinforce chords; nor do they spread them in the Largo to replace serenity with rhetoric. And is the variation to the rhythm between 1'49" and 2'02" in the finale meant to create outrage? Or highlight humour?

Pletnev is an entrancing musician. How so begins with his total control of the whole instrument, not just the keyboard. He plays into the piano, using its in-built resonance to extract a range of prismatic sounds devoid of harshness. And his left hand has a sovereignty of its own, so bass-lines often acquire unusual significance. Co-ordinate such mastery with profound responses to the music, and extraordinary interpretations follow. The emendations, particularly the addition of harmony to Beethoven’s exposed treble towards the end of No 3, may seem downright impertinent. But that’s Pletnev. Try to ignore his “solecisms”, because the total experience he offers (which DG could have enhanced by not spreading the piano from centre to extreme right, and pulling it closer for the cadenzas) is something else.