SigComing from the old iBasso D2, there is really not much improvement here. The iBasso dac amps are great products. I am slightly disappointed with the D4 mamba because I found that at higher volumes, there is not enough voltage between the DAC and another part, which causes sound wave clipping. This is a serious drawback and almost requires modding to fix. If you don't plan on cranking the volume all the way up or you dont mind soldering a resistor on after doing your homework, then this is a really good amp. In a side by side comparison, my iBasso D2 viper has zero audio clipping issues at equal or slightly higher volumes. The D4 volume knob has significantly more room to go over the D2, which is probably at audio levels that would damage hearing. This is without gain switched on.