For a long time, I had an Asgard 3 & Modius stack exclusively for my 6XX, and a Cayin RU6 for everything else.
Upgraded to an R2R Fiio K11 last month for better form-factor & user controls, and of course, it turned to sound similar, but more refined.
Beginning of December, I randomly saw the Nitsch Piety on Apos, and impulse bought it because I was very interested in what tubes might sound like.
Until recently, I had one pair of RCA cables, so when the Piety arrived, I swapped out my Asgard, for the Piety. To summarize, it sounded like an Asgard but warmer & funky on low gain, and like an Asgard 3 Jr. on high gain. Very cool.
The RCA cables I use are made by JDS Labs, and are 6 inches. Because the Piety & Modius have a homogenous design, they could easily stack with such short cables. However, stacking the Piety on top of the K11 required 12inch RCA cables (see image).
To circle back, I recently acquired some 12 inch RCA cables, and stacked the Piety on top of the K11. I figured it would be plug & play, but no matter how much I tinker with the K11’s settings, no noise comes out of the Piety.