You have the right idea regarding purchasing a new DAC to use with your Bluesound. It is common knowledge that the Bluesound DACs are the bottleneck of any of the Bluesound units.
Regarding those suggesting you replace your freya+ preamp, it is true that it is not the highest cost unit, but from every owner and professional review it appears to come as close to being one of the highest bang for the buck preamps on the market. Maybe change the flavor with some new tubes.
Just be aware that often those recommending you flip your gear to what they have now will have totally different gear in a year or two and be just as hardily recommending that gear then.