Dear Suba,
Thank you very much for your answer.
The workaround you wrote above does help to make the calculation cleaner.
Cheers,
Fabián
There is an issue with how TransferFunctionModel is handling these expressions.
A workaround to get the series connection would be
TransferFunctionModel[Map[Together, tfMimo[s] . tfMatrix[s], {2}], s]
