You requested recommendations for high sound quality classical CDs. Here you go.
Beethoven 9: Sir Simon Rattle, Berlin Philharmonic (issued 2016). If you can't buy the individual CD and don't want a digital download, go for
Osmo Vänskä's 9th with the Minnesota Orchestra, on the BIS label.
Mahler 4th: Adam Fischer, Dusseldorf Symphony
Brahms 4th: Andris Nelsons, Boston Symphony Orchestra; or Riccardo Chailly,
Gewandhausorchester
Dvorak 9th ('From the New World'):
Andrés Orozco-Estrada, Houston Symphony
All of these are recent recordings (within the past 10 years). For quality of performances and sound quality, check the online reviews.
Hope this is helpful.
TimT