Why Do Some Recordings Sound Great and Others Dead?

@OP - If you feel uncomfortable, here's my recommendation:

Corner Bass traps or soffit traps from GIK.   The soffit traps work a little better, but the corner bass traps give you more floor space.

Not sure if RP is the a good reference or not as I don't use that service, but there are a couple things to consider. 

- If you don't know the CAT # of the specific album, well that is a major prob.  That is also a big downside to streaming - you have no idea (many times) of the provenance as well as they can remove/change said album version at any given point and you'll never know (generally speaking)

- The recording/mixing/mastering means everything (provenance) and if one doesn't know that then all bets are off

- Some recordings most def sound better than others (I would hope so)?  However, as has been pointed out, the room/acoustics are paramount to SQ along with proper setup.  Those two items are an absolute MUST before anything else. 

i also believe in "tone control courage" IOW using definitive electronic means to correct an incorrect frequency balance in a given recording. 

With my current setup I don’t have any tone controls.  The NODE has some when using the internal DAC.  I’m bypassing that into the SMSL DAC, which has no tone controls.  I don’t have a preamp, and my speakers are powered.  I’d have to put something into the system like a Lokius, minidsp or minidsp ddrc24.  There are some crossover frequency and q controls on my subs.

Some recordings sound great and others dead because of differences in recording, mixing and mastering.

I hear five different classes of sound quality in my collection of albums, even ranking each album D, C, B, A, A+ based on sound quality only.

This has nothing at all to do with the "music quality" of the material or the artists.