Whats the difference ...

Engineering corners have to be cut in order to make those units affordable and fit into one box, so the differences are not always apparent or discernible from the specifications. Quality power and shielding between analog and digital components is probably the first thing to go. There are high end combo units that do address these factors, but they may not be considered affordable by many.

Audiophiles like separates for their singular focus and the ability to upgrade piecemeal when upgrade fever strikes and budgets allow. I agree with others you might want to try a streamer upgrade, Innuos is a safe bet, I would leapfrog over the Bluesound. I have a Gungnir myself, which I have recently replaced, it is a very good DAC in that price range. If you have not done the multibit upgrade, I highly recommend it. 
 

very much depends on the role streaming plays in your listening, both as relates to sound quality and software ease of use...I also use an Oppo 105, but thinking my small, inexpensive WiiM might sound better into a good DAC like you have...

@hsounds I did indeed use my Oppo as a streamer for years, but then the app interface went down and Oppo no longer supports the 105 or the app; thus I had to find a workaround. 

@soix @erik_squires Thanks for the words of wisdom and for putting things into perspective. 

@zlone yes, the Multibit upgrade is on the horizon - once I get my retip Hana cartridge back and paid for!