Yoel Arbeitman wonders:

>My question really concerns what composers are deemed equally great as
>both opera and symphonic composers.

Well, Mozart, for one.

Berlioz, maybe.  Strauss, maybe, if you count the Alpine Symphony or
Heldenleben as a symphony.

I happen to think the world of Vaughan Williams's operas and symphonies,
but I'm probably one of a handful who's heard all the operas.  And, of
course, not everyone thinks VW a great composer.

But it is true that most opera composers were professional opera composers.
They stuck to that, pretty much.  Now, I'm not so sure the distinction
is as meaningful, since there's very little life in the current opera
scene.  An opera premiere is a special event these days, rather than
something you expect every season.  It's become a rather recherche art,
like symphonic music, instead of entertainment mainly to be enjoyed.

Tchaikovsky as a great opera composer?  Sure.  Onegin and Pique Dame
alone are terrific.  They're also the only Tchaikovsky operas I've heard.
I have no idea what the others are like.

Steve Schwartz