Branimir:
Jonathan is the man to talk to. His website is www.chambersaudio.com. He knows the DarTZeel inside and out. I own two of them vertically biamped, and I'm in awe of their sound. The pricing is unfortunate, but that's the result of the weak dollar more than any greed on DarTZeel's part. I've listened to the Boulder 2050, I think, and was not impressed AT ALL. Very clinical and mechanical sounding, IMO, though very powerful. The Dart is the polar opposite, and even more transparent and detailed. The overall sound is as pure and natural as I've ever heard, even from some of the world's best tube amps. If I hear something better, I'll get that, but I've yet to hear anything better.