Justin has created a masterpiece! I have the headroom micro, IQube, ray samuels sr-71b, and ALO Continental (tube) portable amps. The Pico Power beats them all and it's not even close (of the aforementioned ones the Continental compares the best, but still, it's no even close. My source is a humble Sony Discman player I bought in Amazon (used from the early 2000s; cost less than $50). Used the Telarc recording of Wagner overtures conducted by Jesus Lopez Cobos with the Cincinnati orchestra to try and stress the amp as much as possibli given the wide dynamic range of the recording. I played the Rienzi, Flying Dutchman, and Tannhauser overtures with the Fostex th-900s, Ultrasone edition 8s, and audio technical 3000ANVs. All of these headphones have never sounded better out of a portable amp. Great bass, great minds, and great treble. Nothing is exaggerated or awkwardly salient. No roll-off here, there, or anywhere. I'm not kidding when I say that this little gem of an amp sounds like a full fledged desktop amp costing more than $1000. Most powerful portable amp EVER, PERIOD! Power and finesse all rolled into one. The search is over. With my other portable amps it was always like, "it's okay, but...". There are no buts with the Pico Power. Amazing. This is the end of the journey for me when it comes to portable amps: I'm not buying another portable amp unless it is to replace a broken Pico power with a new one. I'm smitten. I'm in love. Is this a rave review? Ya betcha! This is a groundbreaking product, Justin. You are a master. Two years in the works and now I know why it took so long. Congratulations! Between this and the blue Hawaii you have become a living legend.