I have several iFi nano IDSD and an iFi micro IDSD and a Korg DS-DAC 100. The two nanos are probably most suitable for driving IEM's but the micro
will drive any kind of cans nomatter the load.
I use the micro in the living room system powered by the iFi micro iUSBpower and the iFi Gemini usb cable. The tiny WIN8.1 pc is running JRMC v20 and is connected to the iUSB power by a cheap but very short (20") Belkin usb cable. All of my ripped and downloaded music files are on a small NAS elsewhere. The micro iDSD functions as one of the finest headphone amps available, being adjustable for the cans its driving. I use the analog outs to an AudioEngine N22 and then to Louis' compact hemps and a sub. There is also a turntable and phono pre that are getting used less and less because of the quality that DSD provdes.
My bedroom system has the Korg DAC and Audiogate software which allows one to upconvert flac to DSD128 and there is an older Decware Zen amp and the Parker95 mkII speakers which are terrific w/ this low impedance amp. I also use the iFi iUSB power unit and Gemini usb cable w/ the Korg DAC. This a wonderful, sweet sounding system that is difficult to shut off and go to sleep.
Larry