this small (slightly larger than a box of tilt) d-class amplifier expresses his 2x40W + out very clean - not a cause for action. The build quality is SMSL-typical very good and that the air-core coils for switching frequencies and skin effect and something warm (approx 50grad c), does not bother me as long as they do a good, natural sound (see also SMSL SA-160) , really really cool + classy, the part as machined from billet aluminum, and sounds to my 20-year-old 2-way 4ohms ELAC and 6ohm Onkyo remarkable well-defined platform, deep bass + dry, clean middle + heights. The 100W power supply is ok and need not be replaced and even the A / B-class headphone amplifier funzt well with my AKG K500 (much stronger than directly on Smartfon) for the time being. Conclusion: I am (exceptionally) pleased with my purchase. 1st tip: First 30 hours + "import" (let it run) 2. Tip: optical and acoustic ideal for broadband projects, like "fosticon, lancetta, needle, Tuby, creature", etc.