All those of you on this thread who may be curious about NOS sound have a last chance to pick up an HM-603S for cheap here in China: https://detail.m.tmall.com/item.htm?id=36982945742&sid=9fca2e94f62e378d294d1a6ff6f9d158&rn=227d3cb8fd20c5a62385ae157d599740&abtest=5&sku_properties=5919063:6536025 Just one example - there are several other Taobao sellers. The 603S is basically a 601 with the amplifier section of the 603 (no USB DAC capability, but enough power to drive full-size cans). It seems that they are offloading their last stocks of TDA1543s. I do feel that it sounds slightly better than the HM-601LE (enjoying mine through Dunu DNKs as I write this). I will miss cheap and easy access to all this Chinese gear when I go back to Europe in a couple of weeks!