I have both the Node2i and Powernode2i. The BluOS system is nice. I use the Node 2i digital out to my Meridian DSP speakers. What is unique about it is that the digital output can be set to variable, thus giving iOS based control over digital volume. Apparently Bluesound has a proprietary digital volume control which allows digital volume control without audible effects. Another nice feature is the ability to do the first unfold of MQA to 24/96 and output to outside DAC. As for the Powernode 2i, and this strays a bit off topic, but the sound of the hybrid digital amp is very nice. It’s from sister company NAD. Any idea what this HybridDigital amp is?
Digital attenuation is a simple multiply operation. The bit depth is the DAC is important here, but technically, with 24 bit data from after the attenuation, you still get 16 bit resolution even with more than 50dB attenuation, and more bits as the volume “goes up”. There should be no audible artifacts with a properly designed digital attenuator driving an adequate DAC (higher SNR is best). We suggest the 130dB+ Cherry DAC DAC 2 HS/HSV for amazing clarity regardless of the digital volume setting.
Regarding mqa, it’s a lossy compression algorithm with DRM, so we suggest “free” (FLAC, etc.) lossless playback instead, in PCM. All other formats originate from PCM, including DSD, if not direct to disc (no mixing). Albums are mastered in PCM, typically 96/24 these days. The issue of effective resolution is something we’ll save for another discussion. Bottom line is that there’s no need to improve on high-res PCM, and there’s plenty of bandwidth to transmit high rate PCM losslessly. This is why we recommend Qobuz for lossless high-res streaming.