It was a while since I checked out the DSP quality (have been using HQPlayer for that), but it does seem Roon 1.8 improved sound quality on DSP, at least for convolutions (I haven’t tested PEQ or other parts).
I compared the same convolution file from Roon and from HQPlayer, and there is a little difference but now it feels more like a preference than a difference in sound quality. Using the convolution in Roon gave a slightly softer and more laid back sound compared to a more forward presentation from HQPlayer. I could not detect any difference in sound stage or details, which was pretty easy to detect with previous versions of Roon which also sounded to laid back and soft.
Using convolution from Roon does produce less latency though, which is nice.
I will use convolution from Roon for a few days and then switch back and then compare (first impressions are often wrong in these cases).
I can’t weigh in on HQPlayer, but I have been using Roon’s DSP convolution filter the majority of the time since I got my system last August. I started experimenting with REW and your guide (thanks!) but I ended up with the following:
Convolution Filter: Home Audio Fidelity (generic crosstalk)
Headroom adjustment: 0 dB
Show clipping: yes
Volume leveling: Auto
Target volume level: -23LUFS
Volume when unknown: -14dB
With this setup, in Roon 1.7 I felt there was a slight quality degradation when turning convolution and/or volume leveling on. It was like the crispness/clarity of quick notes / clicking type sounds was reduced. However the benefits of the HAF filter, no clipping indicated, and not having to adjust the volume too much between different genres was worth it.
My initial reaction to Roon 1.8, before reading any forums, was the convolution/sound leveling degradation 1.7 had was gone. I think the sound may have changed more than just that, but am still trying to figure that out. I still need to try 1.8 with default settings to see what that’s like.
(Disclaimer: I wanted 1.8 to sound better and it’s 16°F outside right now, so this may just be an exercise in mental gymnastics. )
That’s exactly how I also felt, convolution in Roon dulled the sound, made it a little grey and veiled. Having said that and just compared, the convolution in HQPlayer is still a little step up compared to convolution in Roon, but the difference is much less now. And there is less latency when using convolution in Roon.
I have generally found better results with entering a handful of manually tweaked PEQ bands to each channel after doing EQ in REW, vs generating a convolution filter. Was unclear if that was because of the convolution itself (time smearing etc) or Roon DSP. Given your above comments I will give this another go and see how it fares.
i use the jaakkopasanen convolution DSP on a pair of HifiMan Ananda.
Am very happy with the way it sounds in 1.8
AceRimmer
(Smoke me a kipper, I'll be back for breakfast!)
6
I have been upconverting everything to 384 since about last November as my new DAC, Chord Qutest can handle this and this gave me quite an uptick in SQ.
IMHO this only got better with the change to 1.8.
I have not played with anything else as of yet though.
outside right now, so this may just be an exercise in mental gymnastics. 
)