I can imagine the scene at the Thomaskirche in Leipzig in 1723: a devout congregation packing the church to hear the first major composition from their new kantor, to be awestruck by the imagination, variety and sheer orchestral brilliance that Bach packed into his Magnificat. Last night’s performance by Masaaki Suzuki and his Bach Collegium Japan, displayed some of that brilliance, but failed to overcome some of the difficulties of bringing the piece to a concert hall like the Barbican.

There were highlights – fleeting moments in which the magic captured me. Soprano Joanne Lunn sung Et exsultavit with a radiant expression of fervent joy, while Rachel Nicholls gave us a completely different soprano timbre in Quia respexit: powerful, cutting through the orchestra, well matched to the elegantly phrased oboe solo. In the Esurientes implevit bonis, I was transported by the loveliness of the flute solo and captured by the debonair way in which countertenor Robin Blaze delighted us with how “the Lord hath filled the hungry with good things.” In Omnes generationes, the second of the Magnificat’s four big choruses, the choral entry shook us out of inward-looking humility to make us sit up and listen.

But too often, voices were lost in the relatively dry acoustic, and Bach’s marvellous feats of counterpoint and harmonic shift came across as delicate tracery but didn’t quite bite. The opening and closing choruses of the Magnificat can (and should, in my view) burst from the seams with joy and devotion, and a clear, filigree rendering such as last night's sells them short.

The Magnificat was preceded by a vocal appetiser, Blaze singing the cantata Bekennen will ich seinen Namen. This pointed the way to some of the problems to follow: Blaze showed timbre that was naturally warm and expressive and he would make a fine attempt at starting a note cleanly and developing vibrato colour, but the combination of acoustic and tempo was such that he was unable to fully develop each note before it was time to move on to the next. It all felt just a fraction rushed.

The first half of the concert was instrumental, starting with the Orchestral Suite no. 3, whose second movement Air, in its transposed and rearranged guise as Air on the G string is one of Bach’s greatest hits. For me, the performance here showed that the original is best: the different accompanying lines interwove and supported the melody, each line taking its turn to create the harmony, gently, deliberately calming the soul. Shorn of any attempt at overt, vibrato-laden romanticism, the performance was simply exquisite.

I wasn’t so taken by the performances of the faster movements. Partly at least, this will be because of my seat position: I was quite close to the orchestra at its far left, next to the imposing trumpets and timpani. These were rather overpowering and sounded slightly disconnected from the main wash of string sound, and I struggled to hear cellos, bass and harpsichord. But also, the light, deliberate accenting that served the Air so well left me wanting in the overture and the gavottes, nor did I really get a dance feel in the closing gigue.

The same pattern was repeated in the following Double Concerto, with the two violinists accompanied by an orchestra severely pared down to a one-to-a-part string format plus harpsichord. The slow movement worked beautifully for me, but I missed the exuberance of which the outer faster movements are capable. The two soloists had very different timbres: Ryo Terakado sounding strongest and clearest on the upper strings, Yukie Yamaguchi on the lower. The playing was precise and their timing was together, but I had no sense of energy feeding from one to the other.

Maasaki Suzuki cuts a charming, avuncular figure on the podium. I thoroughly respect the subtlety and sensitivity with which he and Bach Collegium Japan approach their music. But apart from those wonderful slow movements and a few moments in the Magnificat, I had hoped for more.