To answer your question... all types of music files (MP3, flac, wav, and all bitrates (128, 320, 1100+ hi def.) .
If I try to toggle the Directsound plugin that is in the plugin section here, the sound acts like I have vibrato on as soon as I enable the plugin...... it pulsates at a very high cycle, as if hearing it through a fan...hard to describe.
I can't get past that to even use the Isotope and if I do load the Isotope through the plugin, it loads, I can see it on the screen, can highlight it, but cannot tick the box next to it. Possibly why the sound is not routed through it?? But believe me, Isotope really spices up the sound and in my opinion gets rid of much of the muddiness. It puts a lot of life back into it being more punchy and brilliant.... The instruments even seem to be more defined and separated.
I thumbed through the weirdness files and could find nothing to fix my issues
I also tried the DFX plugin and got the same vibato effect with lots of noise added.
I am using a Creative Soundblaster Live card and coming out through SPDIF into my amp.
Oh well, we'll live.