I decided to drop a note to Napster Support so they would know that there are at least two people that want Napster to work with their Sooloos. I received the exact same reply as you did. The boilerplate reply does indicate that we aren't the only ones notifying them of the problem. Since they didn't say that they no longer support Sooloos, there is still a faint hope that one day it will function again.

QNAP, MS600, MS200, Anthem AVM 50v, B&W 804S, JL Fathom 113 (2)