If you think of Madrid and Sevilla, respectively, as New York City and New Orleans, then you get a better sense of how to think about this.
Suppose you're in NYC and you want to go hear Delta Blues and also have a Cajun dinner -- can you find them? Sure you can, it's NYC, where you can find anything and everything. You can even find a club and a restaurant where the performers and proprietors are from a long line of blues players and Looziana chefs -- but their work is catering to the customers who are there in NYC.
Same goes for Madrid - there are Andalusian spots that are perfectly legit, but they are scrubbed and polished for tourists in Madrid.
Think again about your phrase 'a good Spanish dinner' and go back to the NYC analogy: Would you want to eat a good American dinner while in NYC? If you're there in Madrid, I think what you want is good Castellano cuisine, and maybe (maybe) some kind of overall greatest hits kind of restaurant that includes what outsiders think of when they think of Spain. I personally don't go for that as much as regional specialties. What would a good American dinner even be in NYC? How about in Chicago or Los Angeles? Bring that perspective to Madrid.
My personal experience: I've done the full meal at Tablao Arenal in Sevilla and it was exceptionally good, and reflective of southern dishes overall, with a bit of but not too much greatest hits included -- tortilla and bacalao starters, duck in cherries sauce main, pastel and fruit for afters, wine and sherry and coffee included. Much better seating than those doing tapas only or show only.
(Edited to add that I also wouldn't normally do dinner together with the show but if timing favors it - 2 birds w/ 1 stone - then it can be a good choice.)