I purchased my DS Sr. without a Bridge II. I was using the DS’s USB input at that time, coming out of a MacBook Pro running Audirvana Plus v1.5.12.
Eventually, I added a Bridge II to the DS so that I could get the MBP and its switching PSU out of the system. I started feeding the Bridge II with a hardwired Ethernet connection from a Melco N1ZH60 and this setup sounds clearly superior to the MBP>USB>DS.
Newly released Audirvana Plus v3.1 can now stream to UPnP/DLNA network players, so I thought I would give it a try. Yes, I can stream from A+ v3.1 directly to the Bridge II, and that sounds at least as good as streaming to the Bridge II from a smart device control point app such as Bubble UPnP. But the real surprise was controlling the Melco via A+ v3.1 and feeding the DS via USB from the Melco. (My USB cable is the Revelation Audio Prophecy CryoSilver Reference DualConduit USB 2.0 Digital Link.)
The Melco via USB into the DS sounds way better than the MPB via USB into the DS, and that is to be expected given that one is a dedicated audio device and the other is a consumer-grade laptop with a switching PSU. But, comparing the DS Sr.'s USB input to the Bridge II’s Ethernet input with the Melco as the source for both, I was pleasantly surprised that USB held its own. And because A+ v.3.1 has built-in MQA decoding up to 24/96, I do not miss out on MQA entirely by bypassing the Bridge II. (The Bridge II decodes MQA up to 24/192, but only if you use the ConversDigital mControl app. I and several others have found that app to be somewhat less than stable at times.)
One thing I like about using the DS’s USB input as compared to the Bridge II is knowing that the DAC hardware’s sound quality is pure PS Audio, with no third-party OEM manufacturer’s networking module or related software impacting the sound.
Am I going to list my Bridge II for sale anytime soon? Probably not, as I am hoping MQA playback through the Bridge II becomes more reliable over time. But in the meantime, I will be splitting my listening time between the DS’s USB input and the Bridge II’s Ethernet input.