Tonight at the CSO: Brahms’s First Piano Concerto, the Rosenkavalier Suite, and Ravel’s La Valse.

Martin Helmchen at the piano; David Afkham on the podium, standing in for Nikolaj Szeps-Znaider, sidelined by an injury that “doesn’t yet allow for international travel.”

I think CSO’s hall has its quirks: the acoustic quality vary seat by seat. My seat today had a fine view, but the layers came out muddled, and I lost the piano for much of the concerto. Afkham might have balanced it better.

I lean toward house left. The high winds — flutes, clarinets, horns — and the cellos and basses all face stage right, so they reach you cleaner.

I lean toward house left. The high winds — flutes, clarinets, horns — and the cellos and basses all face stage right, so they reach you cleaner.

Helmchen chose a lovely encore: Schumann’s “Vogel als Prophet,” from Waldszenen, Op. 82 — hushed and mysteriously listening for something just out of reach.

The balance troubles behind us, the second half landed in the CSO’s sweet spot: a sumptuous Rosenkavalier beside Ravel’s La Valse. They constrast each other — Strauss’s Vienna remembered in gold, Ravel’s dissolving into smoke. The orchestra was fully in its element. A great night.