Why Do Some Recordings Sound Great and Others Dead?

i've noticed there is a wide variety in sound quality from recording to recording, even those made in the same studio with the same people. a lot can go wrong between the studio and your listening room, at multiple steps along the way. some recording studios [particularly classical labels] try to ameliorate this situation by using consumer equipment in a consumer-type of studio listening room, to make their sound something that sounds more reasonable in a typical home listening environment. i have found that for most situations, a certain modest amount of dynamic range compression/limiting is helpful to make a given recording sound the best in the universe of different listening environments/equipment complements out there. there is an artful way of doing this which doesn't do [as much] dirt to the lucky owners of megabuck equipment and megabuck listening rooms. a light touch is required, but not all recording professionals have a light touch, as witnessed by the thousand and one sins one hears in commercial recordings. the biggest sin IMHO is mixing the vocals in a way that they are barely discernible from the musical background, i believe the germ of this idea came from hollywood movies with their emphasis on "realism" IOW maximizing the [relative] impact of the loud parts by reducing the volume/clarity of dialogue. a lot of artists don't care to have their vocals too high in the mix [Elvis was a notable example], and the engineers are all too happy to play along. i have [per audiological exam/spectrogram] normal hearing for my age, so when i hear muffled vocals listening on my Sennheiser HD580 cans, i know something is wrong with the recording. 

@erik_squires  Thx for your explanation.  I reread it, and I can appreciate the considerable time and expertise in your analysis.  I don’t currently have enough knowledge to follow up on it with any confidence. My room is a mess, but I  can’t do much to improve it.  I tried following various suggestions and acoustic placement principles, but with 2 Beolab8000 speakers, 2 subs and an unwieldy room, I’m just guessing.  I’ve worked on speaker microadjustments,  Next I’ll try the subs.  Since my speakers and subs are all powered, I’m not using a preamp with the SMSL M400.  I wonder if that could be a problem? Maybe some day I’ll have more confidence to try minidsp or Dirac.

@emrofsemanon  Thx for your comments!  I just listened to May Erlewine’s ‘Days Gone By’ and her voice was very forward, loud and clear.  I believe the same is true of the Nora Jones recording mentioned above - but it just does not come through on my stereo system.  Until I get it ‘fixed’ I’ll just listen to what sounds best for me. 

@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.