(Photo credit: Sylvia Elzafon) The Dallas Symphony Orchestra (DSO) has announced two additions to its Next Stage Digital Concert series. Franz Schmidt’s “Das Buch mit Sieben Siegeln” (“The Book with Seven Seals”) and the DSO’s new Symphony Stream are now available on the DSO’s YouTube channel. The upload comes in time to honor the year of Schmidt’s 150th birthday. Grammy-winning {…}