Found no mention of this product yet and wanted to discuss its principles. Original design discussion sparked on diyaudio forum. It is an FDA amp with PWM modulator in the analog conversion stage. I haven't really run into anything like it yet, but I'm very intrigued. It uses direct drive, no feedback output over 2.5mm balanced. See design label: On top of that it has an iOS/Android app called HPTOY that can tweak DSP settings over bluetooth, including PEQ profiles. Asking price over contact form/paypal is like $60-ish bucks, $5 if you want a usb split cable to use external power (for using with smartphone for example). Pretty cheap, no? Seems like a fun toy. Website and details here.