Quoted from bobukcat:No circuit or power transformation solution is 100% efficient, there is loss in every method available to do this so why spend more for something electronic based that could fail, will generate heat, etc when a simple, low-cost transformer will do the job?
Additionally, the transformer is lower loss than those other methods would be. The only downside to a transformer that I can think of is that fluctuations in the input level will show up in your output. If the output doesn't need to be a rock solid 24VAC, the transformer is the best method, IMO.
