Simple question to all audiophile gurus out there:
Can your ears differentiate between original DSD256 track against the same track in FLAC, upsampled via Roon DSP settings to DSD256?
I am doing exactly this using Matrix Audio element M and both are EQUALLY pleasing to my years … what am I missing?
Bit of an open question, it depends on your ears 
… and your imagination. 
What you’re listening for at this point is subtle and would require training or someone, well versed in hearing digital filters / conversion artifacts, help you to identify the difference. It may not be obvious what is changing without this. You can possibly teach yourself if you dive deep into the artifacts of PCM encoding. You’ll need to understand things like phase and ringing. Some people are simply more sensitive these artifacts than others. For example do you care more about pre-ringing or linear phase?
Can my ears tell the difference? I can usually comment on the difference between PCM vs. DSD in a lot of tracks but I’m personally not qualified to tell you what is causing that difference. I only know, after extended listening, what I prefer (and I generally prefer DSD).
And I eg you are under. 50
At 70 I’ve no chance
Well, would be 70 in six months!
Even with declining hearing capacity (no, I am not on hearing aids as yet), I am very pleased with upsampling all non-MQA tracks to DSD256 via Roon DSP settings. At the same time, a pleasant surprise to notice that Roon does not disturb MQA!!!
Roon / Tidal with Matrix Audio Element M as endpoint, I achieved a perfect union (albeit for a 70 year old 
)
By the way, the Element M is on WiFi but never had any problem re RAAT stream…
I posted a similar question on another forum and the answer I received was DSD=Doesn’t Sound Different 
The other factor is the system through which you are listening. Some will be able to resolve differences, others might not. So, like most things, it depends.
I think it’s does matter if the FLAC is 16b/44.1KHz or 24b/192 KHz before up and resampling it to DSD256. You are not clear on the source quality of the compared FLAC.
Upsampling to DSDx makes a difference in my system, but it doesn’t always make a positive difference for me. So many variables.
This morning DSD64 upsampling of 16/44.1 sounds great, so I will leave it until it doesn’t anymore. Let your ears and head make the judgement but keep in mind that if it doesn’t sound so great, you can always turn it off with a tap of a screen. I LOVE the flexibility of DSP options in Roon. We have the best of so many worlds. 
Depends on your DAC. Delta-Sigma DAC (the majority) may benefit a DSD upsampling, if Roon algorithm is better than DAC’s. Internal DAC upsampling may be better or worse than Roon’s but in most cases there is a double upsampling : for example 44 to 192 khz by roon , then 192khz to 352 or 700 kHz by internal upsampling, which is not a good thing, and in most cases, worse.
Apart DSD upsampling for D/S, the only valid case is with NOS DAC, where there is no internal upsampling and so no double upsampling. With USB or I2S input to upsample to 350k or 700k. I am in this case and I hear indeed differences. But there is no better general algorithm : an algorithm may be better with strings (smooth, linear), other better with voices (smooth, minimum), and depends also on music style.
This is the reason why a filter setting by album would be a nice upgrade to Roon.
44.1 to 192 is the worst possible example of upsampling. Because it changes the clock. Good DACs have to clocks one for 44.1 and one for 48 multiples. Depending on the chain you may get good results upsampling if you use power of two (that’s the option you may choose in Roon), but changing clocks will produce crap most of the time. That what Android clock change does to CD quality on most phones.
My DAC does does not touch 192 or 176.4 files, and in this case it is really the question of preference: upsample in Roon or to leave it alone. I upsample most of the tracks to max power of 2 multiplies.
Yes I know. I didn’t want to complicate my message. Just change the Khz I gave by exact multiples, and my message, and what I meant, stays exactly the same ! My message concerns DAC architecture dependance and double upsampling.
Are there recommended settings to choose in Roon?
That may be better answered by Roon developers but in general:
*do not change the clock, that means do not go from 44.1 to 192, or from 48 to 176.4, for example
Other than that it is about listening and preferences