“To be or not to be?” is a question that’s everywhere at the moment. The Barbican’s Hamlet has attracted controversy for initially putting this soliloquy at the top of the show, and Shakespeare’s haunting question could well have been the title of the first of the Boston Symphony Orchestra’s two Proms this year. Existential anxiety hung heavy over both pieces in the programme, Brett Dean’s Dramatis Personae and Mahler’s Sixth Symphony, posing a heroic protagonist against the slings and arrows of outrageous fortune and demanding of them: “to be or not to be?” In Brett Dean’s case, trumpeter Håkan Hardenberger struggled to affirmation, whereas Mahler’s brings us one of repertory’s darkest statements of deathly despair.

It almost seems a shame to write in full about Dramatis Personae, as to give the end’s game away might spoil its shamelessly slapstick effect. Suffice to say that, after a litany of modernist wanderings, a comical march breaks out in a separate trumpet and trombone, with the orchestra’s bitonal shudderings gradually give way to a full-blown Ivesian showstopper of mock-pompous abandon, a climax only suggested before a bathetic, absurd whip crack ends the piece.

Dean’s 2013 work is inspired by theatre; written for Hardenberger, it exploits movement and the performers’ placements on stage. After the first movement, two of the orchestral trumpets come to stand either side of the orchestra, and are ‘led’ by the soloist in rushing figures for the final movement, “The Accidental Revolutionary”, imping Charlie Chaplin’s classic Modern Times, in which Chaplin inadvertently becomes the leader of a group of striking workers – hence the comical ending, in which Hardenberger moved to stand with the trumpet section, joining in fully with the march.

More broadly, Dean was inspired by the characteristic heraldry and heroism that the trumpet conjures, and creates of it a genuinely Shakespearean psychological character study. So, in the first movement, “Fall of a Superhero”, Hardenberger fights against a furiously active orchestra, and fails, drawn into the tumult amongst decaying slides and whoops. Then, a “Soliloquy” which sets up a nocturnal atmosphere before a climax leaves a near-silence for the soloist to spin out a moving, long-breathed tune; one of very few in the piece, and a moment that Hardenberger milked brilliantly. This self-actualisation sets up the final movement as an image of reconciliation between two previously opposed forces. Hardenberger’s playing was incredibly accurate even in hair-raisingly angular music, but the sheer virtuosity of the orchestral parts made it difficult to feel the solo line was anything but another voice, as opposed to the superhero Dean imagines.

So to Mahler’s Sixth Symphony. Standing at nearly four times the length of Dramatis Personae, and requiring one of the repertory’s largest orchestras, here it found a very unlikely friend: the Albert Hall’s acoustic. The BSO is a truly magnificent orchestra, and the sheer sonic richness produced by innumerable string desks, nine horns, and a brass section on very high risers meant this huge empty space felt fuller than I have ever heard it. Even better, everything was miraculously clear; Mahler’s orchestrational prowess deserves some credit, but warrants the highest praise for finding such a perfect sound even in this troublesome acoustic.

The players of the BSO and Nelsons also found a huge range of characters, never letting the music settle into a rut. March-like dotted figures in the first movement were extremely aggressive, and the scherzo’s opening, taken very quickly, was truly terrifying in its fury. For me, most impressive was the sense, even in the pastoral interludes of the first movement or the more consolatory sections of the finale, that this was a doomed journey; by highlighting the easily-overlooked entries of the ‘fate’ theme on the timpani or snare drum, a wholly appropriate atmosphere of doom hung over the performance. Only a gorgeous reading of what is surely Mahler’s finest slow movement gave some welcome compensation, before the finale plunged us harrowingly into the abyss.

Unfortunately, the whole was more than the sum of its parts. Perhaps the biggest issue was the balance of the orchestra; the brass was far too loud most of the time, entirely drowning out the strings and woodwind, with the principal trumpet’s extreme vibrato and excessive volume simply too much from start to finish. In the first movement’s solos, it worked well, but the finale is so contrapuntal and so richly orchestrated that the prominence of the first trumpet lines left the orchestra sounding too staid, and covered up myriad important details, particularly in the strings. Moreover, there were frequent splits and imperfections from the brass section, particularly the horns, which broke the spell one too many times. A few mistakes would have been forgivable, but one too many and the magic, which hovered so tantalisingly in the distance, was unfortunately driven away.