Please tell us can you hear the difference between teac and su 8....It must be extremely small......you might not hear it.
If you look carefully, notice that the rack handles are missing. I’ve owned the UD503 for just under two years and after about 18 months, I thought I was imagining that the sound quality was deteriorating. Things gradually worsened to a point where it became apparent that there was a fault with the electronics. I initially thought that I had damaged the unit with a large static discharge but now doubt that this has anything to do with the fault.
After taking the UD503 apart and running a few tests, it turrns out that the volume control chips are misbehaving and the output from the NJW1195A chips are unstable. The problem is temperature related and worsens as the unit heats up. I need more time to zoom in on the exact cause.
I also spent some time studying the circuit and feel that I can improve the DAC’s noise performance with a few simple mods. Teac took some surprising shortcuts for a Reference design and I plan to follow the AKM evaluation board manual more closely than Teac did.
So, to answer your question, the SU8 sounds better in this instance but I doubt that I could tell a good UD503 apart from a SU-8.