[Dune] Solving Ax=b with A being a matrix of sparse matrices

[Thomas Witkowski]

Is it possible to use the dune solvers to solve a linear system of 
equations where A is a small (2x2 or 3x3) matrix of large sparse 
matrices? I've created a matrix of type Dune::Matrix<  Dune::BCRSMatrix< 
Dune::FieldMatrix<double, 1, 1> > >, but the program does not compile. 
It seems that the type Dune::Matrix<T> is never thought to be used in 
Dune::Preconditioner and Dune::InverseOperator. Is there another 
matrix-type I can use for this purpose?

Regards,

Thomas