The standard instrumental ensembles for opera concerts
First, let’s state that the standard for performing opera concerts is the voice with accompaniment of a symphonic orchestra or piano. So it is at Metropolitan Opera House in NY, Covent Garden in London, Academy of Santa Cecilia in Rome, La Scala Theater in Milan, etc. So it is in all the major theaters and the major musical institutions in the world.
Therefore, apart from full symphony orchestra and piano no other ensemble is used to accompany opera singers during a professional concert. With the exception of course for the Baroque opera.
This means no string quartet, no strings and piano and so on, performing opera concerts.
The reasons why instrumental ensembles other than the standard ones are not eligible
A string quartet is intended for chamber music. It is never used for opera in an opera house: it could never sustain a powerful lyric voice. Worst if it is a duet.
Likewise, having a string quartet with a piano does not improve the situation that much. The piano should play softly so as not to overwhelm the strings.
All the great opera composers have composed their operas on the piano and only after completing them they orchestrated them.
When the conditions for having the broad instrumental ensemble normally envisaged by the composer are not met, or when vocal chamber music is played, originally written for voice and piano, the only professional alternative can therefore be the piano.
In a concert hall with a hundred seats or so you can’t do otherwise. And this has its great charm for the audience: the proximity of the artists and the feeling of participating in a private concert, like those that were so popular in the nineteenth century.
The concerts realized by RomeOperaConcerts
RomeOperaConcerts therefore realizes its concerts with the accompaniment of the piano. With great professionalism and high quality testified by the many enthusiastic reviews received over the years.
Because in this field, we reiterate, the only possible professional alternatives are the complete orchestral ensemble provided by the composer and the piano. Those who represent the true state of the art.