I've tried to go to the Sala Clamores twice now - once for Flamenco Fusion music and one for Cuban dance music, but the first time the band was cancelled and the second time I was too tired. It's only a 7-minute walk from my apartment up by the Bilbao metro stop, in a more "authentic" neighborhood away from the main touristy places.
So today I finally went!
Unfortunately I was alone and it wasn't as exciting as it could have been - but the music was very good. Some Cuban street band was playing, and they played quite enjoyable salsa music. I sat at the bar nursing my tinto (Which was 6 euros, by the way. That's double what I've paid for any tinto before, and not completely worth it to be honest.) and enjoying the music. All around me couples were salsa-ing, and if they weren't at the bar, they were sitting at tables chatting away.
The crowd was an older one than I was used to at most places I'd been. I'd say I was the youngest one there by at least 10 years. But it was an interesting, enjoyable, harmonious musical experience.