You checked the DSP settings on the main computer, you mean? Are these the DSP settings for the zone on the main computer?
Options --> Audio --> [zone to configure] (up above the list of options)
The reason I ask is that the DSP settings when playing over the network are in a different location:
Options --> Media Network --> Add or configure DLNA servers --> [server name] --> Audio --> Advanced --> DSP Studio
Basically, think of each entry in the "Add of configure DLNA servers" list as a settings profile that you can apply when playing to any remote zone. Right-click on any remote zone in the main screen, and you will see an option to associate one of these profiles for that zone.
For now, try using or creating a DLNA server profile that does not convert the music at all, but sends the file to the Id without any modification. In the DLNA server profile settings, change Audio --> Mode to "original format", and turn off any DSP settings under the Advanced section. (Don't worry, this is separate from the DSP settings you have in the main Audio section that you have been using for the last couple of years.)
Does that help any?