I am currently using the legacy NDS, but after the latest firmware update, the system will stop working and reboot from time to time. Not sure if anyone have the same issue.
On a separate note, if that cannot be resolved (since I already replaced the streaming board before), does it make sense to purchase a NDX2 and use NDS as D/A? or should go directly to ND555?
Have you tried a factory reset? This fixed a couple of small issues I had after the latest update. Despite a reset being done automatically at the end of the update, a separate reset, a week later, fixed a small app connection issue and also a hardening of the sound I was experiencing. All working and sounding great again now.
If you want to keep the NDS I think you’ll find that an ND5XS2 is all you need, it uses the same streaming board as the NDX2. An ND555 would be a neater solution, but only you can decide if it’s worth the extra cost for the sound quality improvement you’ll get.