I use my 5400 as a transport mainly for SACD. My Bryston DAC 3 has 4 HDMI inputs and I have 2 of them connected to the Sony and an Oppo 105. Both machines export DSD over HDMI. I primarily use the Oppo for this since I lost the Sony remote but every now and then throw a disc in the Sony just to keep it going.
Sonically they sound similar. The Sony used to reside in a surround system that has become exclusively video. I had replaced it and the previous Blue Ray player with an Oppo 203 to reduce the box count in that surround system and the Sony moved into the 2 channel as an unwanted orphan.
Btw couldn’t disagree more with the OPs assessment of the sound of the Sony. If anything using its native DAC. I thought it was soft, a sonic deep pillow. As a transport playing DSD it’s just fine