I purchased the original SMSL 300SE Desktop DAC/Headphone Amp when it was first released. Now, I notice it being advertised everywhere as an "upgraded/improved" version. Can someone shed some light on the differences between the original and upgraded versions? Are there clear advantages to the upgraded version over the previous one? Is it simply a matter of different firmware, and can I update the firmware to get the upgrade? If so, is it worth the trouble? Thank you.