[...] The tracks seem to come from different sources (probably digitized from different vinyl rips?), and although that isn't a big deal, at least the last four tracks are definitively not lossless audio files.
How that can be possible? It reminds me to the fake lossless digitized by Intermezzi about the I Marc 4 releases on Nelson.
Digital re-issues (meaning official releases coming from the actual label) are a mixed bag, apparently.
We've had the case of KPM 1290 and 1342 whose digital re-issues are good, and better than Hrvatski's recordings from vinyl.
But I've recently stumbled upon digital re-issues which are significantly worse in terms of sound quality than vinyl recordings I also have. And their spectrals didn't look lossy.
Then there was Happy Music's "Music in the ear" re-issue on CD which contained lossy files that the label had tried to "improve" by treating them with an exciter. [(Sub)]'s vinyl recording from the original record showed us how bad the sound quality of that CD really was.
And so on. There even exist vinyl releases that were produced with MP3 material. Nelson's I Marc 4 re-issues seem to be of that type.
In the 1990s and early 2000s (some) library label executives believed MP3 to be sufficient for archiving purposes. Master tapes were destroyed at that time and replaced by lossy files. Now the consequences are becoming obvious.
The case of DMM 308 seems to be different, though. During a quick listen I've not been able to hear that the DMM series' digital re-issues are recordings from vinyl. They could come from master tapes I think.
Greta, if you find the time: why don't you write to Universal and ask them about the source media for these DMM re-issues? And also ask for an explanation for the difference of the last four tracks of DMM 308 from the rest (tracks 2, 3 and 6 look suspicious as well). It will be interesting to hear what they have to say.