I have the Bartha amp & it is based on a concept similar to the 47 labs; had a chance to listen to a 47 for a couple of weeks, and Bartha's amp obliterates it. One of the other great things about getting his amp, you can pick the connectors you want, I had a specific power cord hardwired on, and outputs etc... Recommended that you try to listen to a 47 first, and if you like it, you'll love Andy's amp.