The preamp built into the Emotiva gives the music a very thin, scratchy sound at higher volumes...Im not familiar with how to describe it in audiophile vernacular, but it sounds digital with no richness. So I was hoping throughing in a tube pre after the DAC will clear up that problem.
This thread and
this thread may be of interest. Among other things, these threads refer to issues with the digital volume control in the Emotiva DAC. If you haven't already, it would be a good idea to try running the DAC through the Sony with the DAC's volume control turned all the way up, with the setting of the Sony's volume control reduced correspondingly.
Although the adverse effects of the digital volume control can be expected to worsen as its setting is lowered, the reason that you may be perceiving the problem to a greater degree as its setting is raised may simply be that our hearing mechanisms become more sensitive to high frequencies (relative to their sensitivity to mid frequencies) at higher volume levels.
Beyond that, I wouldn't try to mask the problem by changing the preamp or amp. The best recipe for success is usually to try to correct the root cause of a problem.
Regards,
-- Al