With my setup (see signature), enabling DAC Correction brought a significant improvement—so much so that I'm happy to trade off higher upsampling rates for it. I’d rather run DSD256 with DAC Correction than DSD512 without.
Before version 5.13, I was able to use DSD512 with DAC Correction with source files up to DSD512.
When I first upgraded to v5.13, it almost worked with DSD512 sources upsampled to DSD1024, but I experienced brief pauses every 30–40 seconds. After experimenting with the Block Per Cycle by raising it from 4 to 10, it now runs smoothly again with source files up to DSD512 into DSD1024 with DAC Correction enabled.
While I don’t really care much about DSD512 sources, as I only have 5 albums in that format and I didn't even listen to them that much, the fact that I can now play them at DSD1024 with DAC Correction using the same hardware is a testament to the significant improvements in HQPlayer.
I actually prefer the sound of the new filter at DSD1024 slightly more than my previous setup, which was ASDM7EC-super 512+fs at DSD512 using the same filters. It’s a shame my system can’t handle ASDM7EC-super 512+fs at DSD1024 with DAC Correction, though.