The legacy streamers can cope with multi room up to 24 bit and 48kHz. If your master, say an NDX, is playing something and you then send it to another legacy streamer, say an ND5xs or a Qb, the NDX will continue to play at 24/48 but the ND5xs or Qb will be playing MP3.
The key words in David’s quote are on the master device.