I've also had the D1se for a year and half than move to SU-10 early this summer. At first my ears/brain is telling me D1se has a smoother sound than SU-10 which was a bit of disappointment. Fast forward 2 weeks later while I was messing around with Audacity recording and playback. Well, this is where I start to notice songs that was recorded using SU-10 have richer sound quality than D1se during playback on my Arya SE. It must be the brain adapting and adjusting thing, I guess. There is a filter setting on both DAC, and when set to Tube on D1se it sounded pretty good but not on SU-10. I'm not entirely sure why and could be just me.
I was thinking same thing as Rotel and getting a R2R but while browsing last night I saw SMSL just release D400 PRO that had AK9944. There's a YouTube video with sound demo from Thamar where he compared D400EX a higher model to SU-10. Using my Arya SE headset and D90 amp, Grace Mahya voice sounded like she was singing through a tin can, but fine with SU-10 in that video. I thought I was just having hearing issues again, so I put in that same CD (last recording at dug) and play the same track with my SU-10 and it was perfect. So, that was a bit disappointment.
Came across this VMV D2R with no review on YouTube except for 1 but in Japanese, and when I heard the sound demo is where I pull the trigger. Just like Rotel here. LOL - It just WOW!!! I hope it will sound 9/10 as good in my main rig and HP when it arrived, I will be fine.
Rotel - You may want to change your video title and put VMV D2R in front so when people do a search your vid will come up. I didn't see your video while searching YouTube until I came here and saw your post. Thanks for posting that video by the way.
Enjoy listening everyone!