Hi, this is very interesting.
I really don’t want to disrupt this thread and go too off topic but what does up-sampling 320 MP3 (like Spotify) actually do, or how does it improve the sound? Specific to 320 MP3.
Only very high level info required, if that’s possible 
I have many album purchases in 320 MP3, so I’m looking forward to trying out the up-sampling coming in Roon 1.3. I’ve never tried HQ Player before unfortunately.
Same reason it improves redbook.
Understand but at a high level, how does it improve redbook also? I can’t wait to try it with Roon 1.3 but was looking for a high level explanation of how up sampling improves things.
The upsampling itself simply creates more bandwidth so that instead of the audible band taking up 90% of your bandwidth (say), it takes up (say) one eighth of that. This shifts the aliasing up the frequency spectrum so that you can use a simpler, gentler form of low pass filter in your reconstruction stage. Such simpler gentler filters mean the audio spectrum is more linear. This article sets it out in more detail..
If your DAC imposed the same brick wall filter as required for 44.1 kHz on all resolutions, then upsampling wouldn’t make a difference. But most modern DACs will use gentler filters where they can at higher resolutions. Upsampling enables lower resolution content to be filtered using the gentler filters enabled by higher resolution.
This thread contains some recent discussion about the benefits of upsampling.
Thanks so much for the high level explanation. I’l read those links for more detailed info.
Spotify streams Ogg Vorbis, not MP3.
AJ
If your files are lossy, there is nothing you can do to recover the lost information. Meridian upsampling with apodising gives very good results though. People have commented on how well my system makes the best of low quality inputs. DAB Radio as an example.
I put my TV And DAB signals through a Meridian 518 processor first which allows me to add gain. 3dB for DAB and 12 DB for TV in my case.
The upshot is, it sounds as good as it can on my system.
Hi, is Roon 1.3 up-sampling expected to do similar things?
The Roon lads would seem to know a bit about Meridian up-sampling (only guessing) as well as familar with HQ Player up-sampling?
I guess it’s a silly question from me because all will be revealed soon enough. I’m sure many will be doing testing and comparisons when Roon 1.3 comes out ! 
Roon 1.3 upsampling is definitely expected to do similar things. How it works for you will depend on how your DAC deals with hi-res input.
The only publicly available info is set out in point 7 of the DAR artticle. Points to note are that DSD 128 and 256 are mentioned, but not DSD 512. There is reference to a choice of SRC (sample rate conversion) filters, but I would not expect the cornucopia of filters in HQP.
In reference to the original question, lossy 320 mp3 files have problems that upsampling doesn’t solve (as mentioned by @chrislayeruk above). That can mean that the detail which can be revealed through gentler filters is overshadowed by the limited lossy nature of the original material.
Having said that, I happily upsample Internet Radio to DSD 128 in Roon/HQP and I think it sounds marginally better than playing straight from Roon. I can’t rule out confirmation bias as I haven’t gone about it scientifically and the difference isn’t great. Listening to the same track on Redbook local storage does have a qualitative difference for the better.
Thanks Andy.
Not long till 1.3 now. Exciting times !
Come on 1.3!!!
It’s like waiting for Christmas but you don’t know what day it is lol
Hilarious 
No doubt the Roon team is working around the clock. Gotta love major releases and self imposed deadlines (or targets) and all the stress that comes with it. I hope they have decent coffee in their offices for the hard working staff ! lol