Before I can get to what the Arvus H2-4D does and how well it does it, I have to explain why I think it's an important product. I spent years as an advocate for multichannel audio for music, based on discrete, lossless sources such as DVD-A, SACD, and high-quality downloads. All of these were either PCM or DSD and were accessible via a wide range of disc players, DACs, and local file playback apps.