One suggestion that doesn’t cost anything: try turning on volume levelling in roon (and maybe playing with the settings). I like what this does (running a Nucleus via USB into my Nagra DAC); you may not, of course.
Incidentally, I’m not totally convinced that a streamer is always a better option (than going from the core to DAC via USB. I think it depends on the core, the streamer and the DAC.
A streamer is a far better option, because the Nucs power supply is poor. Even with use of a LPS this cannot be solved, due to the build up of computers.
on my system, if you hook the dac instantly to the Roon Core, I get a bad sound and a buzz in my music. A separate streamer is absolutely needed to get a clear sound
Results are evidently system-dependent. There is certainly no buzz when I connect the Nucleus via USB to my DAC. I started off thinking that I got better sound using a dCS Network Bridge via AES to the DAC (and said so in this forum), but, after some minor system changes, I no longer think this. Nucleus to DAC is terrific (in my system).
ipeverywhere,
The CD transport is an inexpensive Sony Blu-ray , coax to the Directstream Sr.
Thanks for the suggestion on the Allo products, will look at the USbridge, and the Microrendu.
JH
My core not a Nucleus is a bepoke silent PC which runs ROCK and also sounds really good to my RME DAC, no nasty gremlins come from this. Previosly I was using a seperate silent thin client running ROCK just as an endpoint so much like a PI really and noticed no difference when I switched to using just the core. Which is great as it cut down on the number of boxes and I could reuse the LPS elsewhere. I am tempted to try a streamer such as the Stack Audio LInk II to see if that improves on anything. I had an Allo USBridge a few years ago and was not happy with it so no interest in the newer signature.
Sadly, and probably, it could be that the USB interface on the DS just isn’t very good. There are cheap ways to get SPDIF and Roon working together (Rasp Pi 3B+ and Hifi Berry Digi+) but I’d go for something a bit more “audiophile” as I mentioned previously. I would certainly focus on the SPDIF based solutions though.
If you hunt the forums here for directstream you’ll run across the Matrix Audio products. This seems to be a “fan favorite” way of connecting to the DS. I believe it even supports the correct IIS for the DS and that is PS Audio’s preferred input.
Or a Pi2AES Pro Audio Shield which also boasts high-quality I2S out for PSAudio… because the “audiophile” bit should be found in the sound, not the looks. But, then again…
Isn’t it the case that the RME DAC has a bit perfect test, which means you could prove that either source sends identical bits?
If it is then also the case that the USB input and the spdif input on your RME DAC sound the same, you have your answer. The USB input on your PS DAC isn’t up to snuff. So changing to a Stack Audio Link II, however good it is, mightn’t help much because that too has a USB output.
I’d spend my money on a DAC with indiscriminable inputs.
My suggestion has nothing to do with your audio setup, but with your ripping setup. You’ve seem to have made the not necessarily correct assumption that the ripping exactly reproduced the cd, but that may not be the case. Try tweaking the flac settings you use with dbpoweramp or even rip to WAV (yes, I know WAV does not support metadata well, but we are trying to diagnose a problem here) and see if that improves the digital performance. Or try another ripper, such as Exact Audio Copy, which is free. Before you start worrying about equipment make sure the source is not the problem.
What about a Pi and a HiFi Berry or DigiOne isn’t “audiophile”?
I really don’t get the animosity towards Pi solutions from some people in the audiophile community. I have a feeling it has, like you said, a lot to do with the cases not being pretty enough for them.
I’m with you. If folks want pretty, the Bryston BDP-π streamer is a Raspberry Pi 3 and a slightly customized HiFiBerry DAC+ Pro board in a nice case with a display. All for only $1.5k. 
Although, I can’t lie, I’m looking forward to when Allo makes a nicer looking case for the DigiOne Signature. 
The made-on-order Pi2AES has an excellent reputation… many believe it can compare with high-end and high-dollars streamers. The cases are no lookers, for sure, but it’s always possible to have someone make a nice custom case and have little audio jewel…
It’s also funny seeing the state of some people’s listening/living rooms while they complain about the aesthetics of a particular component. Like, really?
Beyond that, they’re tiny and not exactly hard to hide away from sight.
Just a Pi by itself because there isn’t design requirements to reduce / remove noise. It’s not focused on all the things you look for like low jitter, low noise, good looks, etc. I still use a regular Pi 4 on my office desk USB into a Schiit DAC. The Pi sits in a Neo case and runs diet-pi. No need for critical listening at my office.
Allo, is focused on low jitter, low noise, and they do (from my perspective) a fine job. Pair their gear up with one of their power supplies and that sits firmly in the realm of an “audiophile” component. It’s just lacking looks and plug-and-play at that point because it does require you do a little work to get the best out of it (reference debate over best pi OS). So, entry level only because it cannot check the good looks and plug-and-play boxes.
EDIT: I’ll add that the Pi2AES fits right in here as well. A very nice HAT loaded with all the audiophile grade interconnects including AES which you just don’t see others including. I just don’t have any direct experience with it.
Then you have Bryston BDP-π. A device they don’t hide the fact it’s a Pi inside. This adds the plug-and-play and good looks lacking in the Allo solutions. A step up simply because of that.
Moving up you have SoTM and Sonore which, are not Pis for sure but I think should be looked at as alternatives since they come within budget of the higher end Pi solutions (especially when you start pairing them with LPS). These are fully custom and meant to be hidden and not looked at so… no reason to fret about audiophile looks there. (BTW, my Allo devices are also hidden). These devices are plug and play and extend the low jitter / low noise by providing options like fiber connections, external clocks, etc.
Then you go big nice box to look at from all the audiophile names and you start getting into the arguments about the benefits of streamer + DAC in the same box to avoid any noise across another interconnect.
Anyway… why not HifiBerry? I just don’t think they compete in the low noise / low jitter space like the others. You just have to look at the complexity of an Allo Digione Signature SPDIF board (pictures on Allo site) compared to the Digi+ (pictures on HifiBerry site). Do I have the test equipment to compare? No. Do I believe, based on simply looking at the board layout, that the Allo will perform and test better than the Digi+? Absolutely and especially when pairing the Allo board with a LPS. I also believe in complementary components. Would I pair a BDP-pi to a $99 Schiit DAC? No, as that kind solution is priced wrong (yes, my opinion). Would I pair a HifiBerry SPDIF board on a Pi with a Schiit $99 DAC? Up until Schiit added Unison to that $99 DAC, absolutely because I know the C-media USB interface was inferior to the SPDIF inputs. So, HifiBerry certainly makes a very fine SPDIF HAT for a Pi at a nice price. I just wouldn’t call it an audiophile grade component (sorry to anyone reading this from HifiBerry).
Gotcha. You just kinda came off like you were talking down on Pi solutions in general. While not plug and play, most Pi solutions should be pretty simple for anyone into audiophile level gear. I like to assume most of us are a tiny bit tech savvy. Great rundown though of the various options.
Wait until you start diving into room acoustics and “investing” in traps, diffusers, absorption, and other treatments. I, personally, have some work to do in this regard but ultimately it does not matter how much you’ve invested in electronics. If your room is acoustically garbage so is your hifi
Hah. I’m not planning on any major outfitting as do I have to live in this space and I like to think I have an eye for form. I’ll find ways to keep the room from becoming an echo chamber without making it look awful. I’m not planning on going above 10’ish’k total for my hi-fi though. If I was, I’d probably invest in a dedicated room.