When members of SBAF mentioned the RU6, it did pique my interest. Wow, a portable R2R DAC dongle. Knowing the complexities of R2R design, particularly those that use discrete resistors, and the need to develop suitable oversampling filters (this isn't the 90s anymore where chips were available to do this, and even back then, they took up significant space), I had my doubts. Those doubts were not unfounded: the RU6 sounds like shit. Take a worn-out 12AX7 and have it try to push something it shouldn't. This is the sound of the RU6. I would describe the sound as kind of a weaksauce, dirty, even strident at times. NOS mode sounds better than OS. This I presume is properly because the oversampling algorithm is garbage. I guess at times the R2R NOS sounds shines through in the form of syrupy lows, rolled highs. In this respect, I feel the RU6 will have its adherents. The RU6's sound is unique and different enough that there will be people who will like how it sounds. However, for me, I'd easily take a iFi GO Blu over Bluetooth than the RU6 over USB. I get what the RU6 is trying to do, but the sound isn't even remotely similar to a Sonnet Pasithea or Abbas Special. While the latter two desktop DACs are in the different price range, the law of diminishing returns suggested that a miniaturized version should be 70% as good no? The RU6 isn't even remotely close because its sound is so utterly incompetent. Heck, the Wolfson (Cirrus) based iFi GO Blu sounds closer to these desktop DACs with respect to lushness than the RU6. Note: my use case was using the RU6 as an AIO into easily powered cans: Grados and ETA Minis from the SE output. P.S. I grabbed this unit from someone who was "curious" about the RU-6.