Is it really unsound?

In the pre-computer engine age, there were a number of gambit openings that were recommended for club players to try. A combination of surprise value and the initiative, meant that they scored pretty well at the Under 2000 level. Then everyone suddenly had a GM level assistant available to them (on their computer/phone) and suddenly a lot of openings went out of business.
Despite this, I'm not convinced that all of these openings should be put out to pasture. One such opening is the Von Hennig-Schara Gambit , which used to be a favourite of Ian Rogers (at least in his pre-GM days). Black gives up a pawn to bring the White Queen into play, and then gains a few tempo chasing it about the board. A lot of players were introduced to the gambit by "The Guardian Chess Book" by Leonard Barden, which had enough analysis to give Black a reasonable idea of what to do.
Even in the age of chess engines, I think the opening is still playable for Black. One model game is from 1931, where Alekhine takes Vasja Pirc apart in pretty short order. Running it through Stockfish, Black always had plenty of compensation for the pawn, and once Alekhine played 13 ... Rxd5 he was easily winning.


Pirc,Vasja - Alekhine,Alexander [D32]
Bled Bled (7), 31.08.1931