Sometimes the small details make all the difference. This was certainly true for the CBSO's matinee this Wednesday. It was a performance that was far from perfect, but at the same time it was the performance that has fascinated me most so far this year.

The opening Five Variants of Dives and Lazarus set the standard for the concert, with a rich and very dense sound that brought to the fore Vaughan Williams' lush scoring, creating a soft tension that gently, almost unnoticeably closed in on the listener. It caressingly tightened its grip as the beautiful score swept over us, beyond the velvety, captivating last notes and refused to let go for several long seconds after the music had faded and Andrew Manze's baton had been lowered.

As it rose again, it was for a remarkable rendition of Beethoven's Piano Concerto no. 2 in B flat major. Whether it was actually Beethoven's first, strongly influenced by Mozart's style, or whether it was his second, showing the composer looking back to his hero, Steven Osborne captivated the personalities of both great composers in a sheer magical way. At no point were we aware that active interpretation was taking place, it was as if the music streamed from him in a natural flow, and only long afterwards did you notice how unobtrusively sophisticated phrasing was, or the shaping of dynamics.

Introduced with a strongly textured orchestral sound, Manze virtually threw little dynamic accents that the orchestra eagerly caught. Then Osborne entered with such a pleasantly soft attack I hadn't thought possible on Symphony Hall's terribly hard piano (which, it has to be said, also has its merits: Beethoven's strong bass lines came out beautifully and carried well through the orchestra without becoming muddy). Osborne's playing was simple, calm and thoughtful, matching Manze's laid-back movements, making the dialogue-like alternating passages of piano and orchestra in the second movement so intensely focused you didn't dare to breathe.

His noble reserve also suited the playful Rondo very well: no exaggerated mannerisms distracted from this pure performance, no dramatic movements accompanied those scales of notes like gleaming beads on strings that still threatened to burst with virtuosity. Even though the solo passages, especially in the beginning, struggled to connect seamlessly with the much richer and softer orchestral tissue (I blame it on the piano), the dynamic agility of both soloist and the orchestra made for an arresting last few bars, and the strong connection between conductor and soloist was tangible and gave the concerto developed a simple and natural charm so strong that not even several untidy cues in the orchestra could break its spell.

After numerous bows, Osborne bade his farewell with a wonderfully contemplative Brahms Intermezzo, making the transition to the concert's second half offering of Brahms' Second Symphony, which Manze conducted swiftly and with plenty of verve, but never rushed. The dramatic passages gained intensity, and the quotations of Brahms' famous lullaby still flowed beautifully in the cellos.

The only fly in the ointment, however, were the aforementioned moments lacking precision that had been a constant if disagreeable companion throughout the matinée. The differences between registers were minimal, but there were noticeable issues with ensemble that are very unlike the CBSO, which found itself only half way through the symphony's first movement, helped by Andrew Manze's more extrovert conducting. Where his gestures had the quality of forcibly contained energy, this energy now found a way out of his slender body and enjoyed the new-found freedom in large, expressive, sometimes snappy movements.

Overall in this performance, it wasn't a certain register that particularly stood out, for me - especially after the "click" in the Allegro, it was the orchestral tutti that created the magic. The third movement was very gracious indeed, the idyllic passages evoking scenes of a fairy tale interspersed with a dance-like element that developed a particularly sweeping drive at the slightly faster tempo and with joyfully sharp articulation. Showing some more of its flexibility and manifold colours, the CBSO leapt into the final movement with engulfing fortes and a tutti piano that was absolutely stunning. Even though you clearly saw the music being produced on stage, the tone was so incisive, yet at the same time had such an incredible lightness to it, that it felt like what one perceived was Andrew Manze's mental image of what the music should sound like rather than it actually being played. This, followed by the joyous, lofty coda led by shining brass, made for an appropriately rousing close to a concert that wasn't perfect, but perfectly captivating – goosebumps guaranteed.