I’ll make a bold claim and say get a Douk U2 pro and a coax cable for like $50-60 and your DAC will sound better than pretty much all $750 DACs plugged in through USB. There’s just something wrong with USB transmission or implementation in DACs and literally none in the sub $1000 range are performing at even 25% of what they are capable of with USB. Detail will skyrocket and not only will you notice a detail benefit from the normal details you hear but the stage handling from the added precision is a massive benefit. I’d put money that most people would say there’s noticeably more detail in an E30 with a Douk U2 pro than something like a D90 without one. It really is that significant and since you have a nice resolving pair of headphones now I’m sure you’d hear the difference immediately and down the line if you upgrade your DAC and amp you’d still be able to keep the U2 pro and use them in the next DAC.