Overall our stay was a positive one - the apartment was spacious and had everything we needed to enjoy the great location during the day. It was secure and beds comfortable. Hosts were quick to respond and also very helpful and pleasant.
However, the apartment is straight above a nightclub. It's not possible to sleep in the master bedroom - even with earplugs you can clearly hear partygoers and loud thumping through hard flooring and air vents (into the early hours every night).
Unfortunately, I can't imagine anything can be done to help unless the nightclub closes.
We had a lovely time in Barcelona, but unfortunately came home severely sleep deprived!