First, don't buy the Bluesound Node, a Wiim streamer (any model) does the same and is a lot cheaper with better dac's.
And digital volume control is often less affecting the sound quality than analog volume control. Both have advantages and disadvantages, but when done right, both will be almost transparent in reality.
You can also buy aan Ncore amp with the (exellent) dac inside, so you can use any digital device on it like the Audiophonics SAW-S250NC. It's an Ncore 252 amp and an ESS based dac in one device. You can connect your phone or computer to it as streamer, or use something like the Wiim Mini with digital (toslink) out to the amp. Both toghetter is 1k€ in their shop.
Nad makes also models that intergrate the Bleusound software with Hypex amps, but they are expensive. It's a one box solution, tested and from a big company with support. But it has a hefty price. The M33 and the M10V3 are models like that that may suit you and both use NC (Hypex Ncore) amp designs, but build by NAD (under licence). That would be the only way i would use the BlueOS, because there the dac is also a lot better than the Node. But a Wiim streamer and a Ncore amp like those from Audiophoncs (next to a lot of other builders) does the same for cheaper. It's just a bit more complex to set up and use.