This is my 2nd Soloist headamp. The first one is Soloist SL MKII which was ordered to drive HD650. Obviously there was some background noise when HD650 was driven by the brand new Soloist SL MKII at high gain and those background noise disappeared with time. For Soloist 3XP, I can’t hear any background noise even at high gain. Burson did a good job in this part. I am happy with Soloist 3XP. It is powerful enough to drive HD800s at medium gain. Surprisingly it also drives sensitive headphone Sony MDR-M1ST well at low gain. The only thing I can complain about is that it is more convenient to have a separate button to switch gain level like Soloist SL MKII.