Thursday night at Symphony Hall, the Chicago Symphony Orchestra marked its season’s first of a series of performances of the Bach orchestral works by the Brandenburg Ensemble. Featuring violinist conductor Jaime Laredo and pianist Peter Serkin, both affiliated with the Curtis Institute, flautists Tara O’Connor and Barry Crawford, and a handful of mostly youthful players, it was a concert marked not by Karajanesque efficiency and professionalism but by the sheer joy of music making. One could imagine that an evening performance at the Bach household did not feel much different.

To be sure, there were interpretive and technical mistakes. An unfortunate bow slip on the part of the concertmaster during a solo section of the Larghetto from Keyboard Concerto #4 in A major was the most egregious of a number of technical mishaps that would’ve made Cortot proud. But then again this was a live performance, and part of the beauty of live performances is that they are not “digitally remastered.” Thus to dwell on such triflings is neither necessary nor productive.

Another more incisive point of controversy, however, was the keyboard element of the concertos. The legitimacy of using modern instruments for baroque music has always been a point of debate, especially when it comes to the use of the piano as a substitute for the harpsichord. Thursday’s performance presented an interesting compromise. The ensemble remained faithful to Bach’s double manual harpsichord accompaniments, while Serkin chose to perform on a nine foot concert Steinway piano. I have never been a stickler for period instruments (especially when it comes to the keyboard), but hearing Leonhardt (harpsichordist), Tureck (pianist), and Wendy Carlos (electronica) all play the same E-flat major Prelude of the Well Tempered Clavier has effectively convinced me that Bach will sound good on just about anything. What did bother me about Serkin’s performance was his occasional relapse into romanticism. Of course, when you’re a Serkin and your grandfather is Adolf Busch, it’s probably hard not to.

At times, the pedal was messy, and the movement to a bass, usually so important in all of Bach’s music, was a little nebulous. Dynamic changes were generously employed, sometimes to the detriment of the ambience, and there was the occasional rubato (gasp!) or accelerando. The violins were not remarkable that night—solid, but a little amateurish. Most of the time they simply dominated the flutes and harpsichord to the point that the flutes and harpsichord were basically perceptible. The cellos were timid; the audience was rarely afforded the treat of hearing them in their full sonority. Overall, slight imbalances of the sections ran throughout the concert, and only in the middle movements, when everything calmed down and the strings were reduced to pizzicatos, was there perfect harmony.

Despite all the mistakes, this was a group that brought life and zest to its performances and made the concert enjoyable. Whoever described Bach’s music as turgid did not see performances like the one on Thursday. Serkin’s positively amazing ability to make the piano sing made for some of the concert’s most touching moments, mostly during the middle sections of the concertos. With the violins perfectly synchronized in their soft plucking, the flute and piano were transformed into a duet, affectionately answering and responding in their precious tones.

Adagio ma non tanto e dolce became cantabile! But this was not Rossini, and duets did not turn into arias. Too often do the musicians of today forget that after Adagio comes ma non tanto and ma non dolce. Kudos to the players for their interpretive fidelity and control; without cheap resorts to vacillating dynamics and tempi changes, they created a sound both infinitely touching and dignified. Another brilliant moment during the concert was the first movement, Allegro, from the Concerto #6 in F Major for Keyboard, Two Flutes and Strings. A reworking of the Brandenburg concerto #4 (showing that even Bach himself was not too engrossed in instrumental purism) was a delightful piece that brought out the best in the entire ensemble. From the incipient sparkling flute trills to the descending piano motives that fell like drops of water to the exuberant strings, you could tell the musicians adored this concerto. The violins and cellos had personality, the piano playing was zestful, and the flutes were absolutely gorgeous. The keyboard scales against the flute melodies were precise, as were the violin pizzicatos. Everything fit together, bringing out the full joyousness of the occasion.

There was a general improvement in technical, interpretive, and coordinative grasp as the concert went on. During intermission, I was doubting the utility of the concert. In the end, though, when everyone took their final bow, I clapped with a satisfied ear and a happy heart. The performance was honest if not technically perfect. The concert was worth seeing simply for watching what joy it is to make music.