I took possesion of my OR5 last week-end. It replaced an HiFace EVO with Boulder powersupply and it was a substantial step up. I was planning to get my Bolder converted to 12v, and then a used Monolith showed up audiogon, which I scooped up. This was a revelation. If you want the most from you Offramp, you need the powersupply. In simple terms, more bass, more detail and generally more musical. Interesting factiod. I use the OR5 with a PS audio perfectwave MKII, but I am not using the I2S, because it runs through a Trinnov digital processor first. I use the DAC in asynchronous mode (it buffers and reclocks the signal), yet the better clocking of the OR5 still makes a big difference.