How to make low end digital sound "not terrible" on higher end systems?

Hi all,
So when I listen to my hyperion CD of Rachmaninov’s Vespers (Corydon Singers with Matthew Best) or The Eagles "Hell Freezes Over" on the below system it’s utterly fantastic. The Vespers is just amazing. I could go on about how wonderful it sounds.
However, when trying low end sources (my iPhone or streaming from Spotify) through the below system ....well, it’s essentially so terrible, it’s almost laughable. It’s just offensive to my senses and really can’t be listened to for any length of time as it’s just very annoying.Is there anything I can do to make it tolerable?
And here’s what I mean by "tolerable": when I’m exercising or just out and about, I’ve got some descent LG ear buds bluetoothed to my iPhone and while the music (either from files on the phone or streamed from Spotify) isn’t like the Vespers mentioned above, I enjoy listening to it. It doesn’t annoy me and I’m into it, I’m captured and can lose myself in the music. I’m "rocking." --I’m not gritting my teeth like I do when it’s played over my below home system.
What I want is to occasionally play a lower end source over my home system and not have it suck as bad as it currently does. ....To at least get it to the level of my cheap ear buds streaming Spotify.I know there are many reasons low end sources sound crappy over good systems but are there any fixes? Some EQ adjuster that’ll at least get it up to where my ear buds are? Or something else?Thanks!

PS Audio PerfectWave transport
Chord 2Qute DAC
Modwright SWL 9.0SE Preamp
Butler 2250 Amp
Modified Maggies (by Peter Gunn)