I didn't really hear noise, per se. There was nothing in particular that stood out as a problem or bothered me. After settling on my power tubes and rectifier, I was happy with the way the system sounded. Nevertheless, I wanted to find other ways to improve it.
I have always conditioned the power to my audio and video systems, and in this case, I heard subtle improvements when I added a power conditioner and upgraded the power cables for the conditioner, amp, and DAC. Adding high end (and overpriced) physical isolation to the amp and DAC made further subtle improvements. The improvements were audible, but at the same time, their value was questionable. By the time I got around to the microRendu and linear power supply, I honestly thought that I was just throwing away a lot of money. To my great surprise, the improvement from the microRendu easily surpassed all of the other tweaks combined. The sound was so much more transparent and revealing, it was like I had a new system. In addition to providing electrical isolation, the microRendu also re-clocks the audio stream, thereby improving the signal to your DAC. (You can read more about it in the reviews and on their website.) Upgrading the USB cable from a Kimber Cu to the Venom was a relatively inexpensive, yet worthwhile refinement. I just added the TP-Links, and found they reduce noise to the microRendu, essentially rendering it more effective.
I like to think of the change in terms of peeling an onion. Each layer of onion removed equates to a layer of transparency and resolution revealed. The combined power tweaks removed 2-3 layers of the onion. The physical isolation removed 1-2 layers of the onion. The microRendu removed 5-6 layers of the onion. The TP-Links removed 2-3 layers of the onion. Hopefully, the onion analogy illustrates why I believe there is so much performance to be gained.
Another way of thinking about it is with power tubes and rectifiers. I started with Sophia 2a3 mesh plates and a GEC u52, and I was like 'eh.' Then I bought some KR 2a3's and a 422a, and thought 'that's more like it.' Then I tried the Sophia Carbon Princess 300b with the WE274b (NOS) and that was perfect. It was like a completely different system from where I started. You can make that same magnitude of change (or more, depending on your situation) by reducing electrical noise. I feel like I am listening to an entirely new, improved system. The qualities of the Stratus and DAC remain, but their strengths are much more evident.
You can buy an inexpensive LPS ($50) when you order the the microRendu, and if you find it worthwhile, then you could upgrade to the JS-2 or similar LPS later. The better the power supply, the better your results from the microRendu. The TP-Links tweak is inexpensive (<$100), but you need to have to a microRendu in place first.
To reiterate, the 'quiet' resulting from electrical noise reduction (and re-clocking) is really about making the system more transparent. It's as if electrical static noise that you never knew existed is gone. It opens up the sound and reveals details that I never knew were present. Music and vocals are much clearer and more refined. Separation is better.
I hope that answers your question.