I primarily use my Ultra for USB hard drive to play music with CD Player using the optical. I use the analog outs to feed my NAD C265 Class D Power Amp. All sounded great and enjoyed the super Android app. I was always curious as to whether a Preamp would in fact make a difference and wasn't prepared to buy a £600 preamp to find out. However since the release and excellent reviews of the Fosi ZP3 Preamp which I found for £140 on Aliexpress I thought it is worth a try. Wow was I wrong this is absolutely brilliant and enabled me to use XLR to the NAD amp. The depth, weight and stereo separation jumped up significantly and I could hear detail that I never heard before, I sat here with a big grin on my face thinking I don't need to tweak any further.