FWIW:

When I first delved into ROON. Th core was iMAC hosted with a BDP pi endpoint. The ROON soundstage was pancake flat vs the BDP/MPD standalone stream of Qobuz and RadioParadise @Redbook resolution. Then I Made a few improvements to the network and cabling but the big move was re-hosting the Core on SGC i5 running the Sonic Orbiter OS (Fedora Linux). Game changer now ROON sounds as good as the BDP/MPD streamer sans the most critical listening.

The Signature Rendu SE is based on the Sonic Orbiter OS.  So +1 for the Sonore.

After looking a bit closer, the streamer market seems fluid with manufacturers revamping line-ups, frequently upgrading models, and increasing prices.  This may not be the time to put money into a newest model streamer.

In the Lumin line-up, the U2 at $5,000 would fit the range while the U1X at $9,200 seems to be the former U1 with a better outboard LPS.

Auralic continues to upgrade streamer models with the Aries G2.2 (that recently upgraded the G2.1) apparently being upgraded to a G3 at $10,899.

I have compared my SOnore Optical Rendu and the Lumin X1 using fibre directly from my network switch. Both sound different and are equally good.

However, I also have a PlayBack Designs Streamer-IF that I bought for $2k. I am only using it with SPDIF out and Ethernet into the streamer (no fibre). I do not know what Andreas K. has done inside that unit but that streamer sounds amazing. Sort of in-between the sound of the smooth and refined Sonore with the loud and brash X1. I plan on eventually getting the PlayBack Designs Dream DAC and then use the fibre stream out of the Streamer-IF. That should be even better.

My Streamer-IF is the previous streamer model PBD sells. I think the new streamers they sell can be used with many more output types, including USB. I would look at them even though they are seriously expensive.

Playback Designs | the finest audio playback in the world

I would think this streamer would work well even connected directly to a noisy computer given the reputation of the designer.

BTW - the Lumin U1X seems to me the internals of the Lumin X1 streamer (what I owned)

@yyzsantabarbara - I remember hearing about Playback Designs and their buffering technology at least 10 years ago. Amazing seems to be a frequently used descriptor. Many praises about the SQ. Pricy though for the new stuff - Playback Designs MPS-X Streamer, $11,500. American company, certainly worth a look.

BTY, I would be comparing any other streamers that I try to a Sonore Signature Rendu SE optical that I picked up a few months ago.  As you said, smooth - like butter on a hot biscuit.  I am currently running the USB into a Singxer SU-6 DDC for purposes of connectivity flexibility.  The SU-6 doesn't change the general character of the Sig Rendu and it certainly doesn't hurt SQ.

Might I put the $5195 Rose RS130 Network Transport up for consideration.

Just put in an order for one after my local dealer let me take their demo unit home for a week. Although Rose has their own app, I used it as a Roon endpoint. Trialed it by both Kimber D60 Coax and Curious USB into my Rockna Wavelight DAC. Also tried I2S, but only had basic non audiophile grade HDMI cable on hand with which to give it a go. Via USB was nice. Via Coax was truly impressive. By comparison made my very competent Bricasti M5 seem congested. Once some things are heard they cannot be unheard. Much more air. Expansive soundstage and imaging. Simply no listening fatigue. And on top of that the unit is drop dead gorgeous. My system lives in the living room, and I had my wife’s full backing when I placed the order. If my dealer would have allowed me to purchase their demo unit I would have held on to it. Most likely will be April by the time I get my unit. The Rose has an OXCO clock, and my thinking is the benefit of that clock is more apparent with synchronous outputs all other things being equal, explaining why my experience with coax was so much better than with USB. My guess is that with a decent I2S cable in my case it would be better still. The Rose allows for connection to fiber via SFP, something I’d like to do down the road. You can also use an external clock if so desired. I very much liked the potential upgrade path.