IEM users beware of noise floor, even for low sensitivity models like the Solaris 2020 (94 dB SPL @ 1kHz: 6.54 mVrms). It seems this is not an uncommon issue for even the most highly regarded portable DACs including the Chord Mojo, so not really a fault, just a mismatch. It sounds great with Focal Clears, but my only use case for the RU6 is with IEMs on the go.
Quality build, sounds wonderful, Comparing with Hidiz S9 pro is in different league. Very happy with the unit after one month. One con - drains iphone battery fast, I guess it needs juice to produce this quality of sound. Using with HD660s 4.4 balanced and Final audio B3 IEM takes away brightness of B3.
An Ares II killer in my 2 channel rig, and I will leave it at that.
The Cayin RU6 has a definite sound signature. It is warm and laid-back, and does a great job of eliminating digital glare that I find most noticeable in the upper midrange. I use it exclusively with conventional home stereo systems - feeding the signal into a preamp - with a Jitterbug between the PC source and the DAC. It’s performance is system dependent. On high sensitivity horn speakers it is great - warm, dynamic, big soundfield depth and width. On lower sensitivity bookshelf speakers it sounds veiled and dynamically constrained. On the high sensitivity speakers I far prefer the Cayin RU6 + Jitterbug combination to other DACs I have such as a Bifrost Multibit, Modi Multibit, Topping E30, and Dragonfly Red.
This is a safe buy