I run my S2 DAC with toslink now, prefer the sound over the USB from Allo USBridge and through ethernet/fiber. Previously I preferred Allo USBridge and USB, but I think since I started running my DAC on battery that changed. The disadvantage is less sample rate and no DSD.
I use a 6V 12Ah sealed lead acid battery connected directly to the DAC (I have heard that LiFePo4 batteries should be even better due to less internal resistance). Fully charged its 6.7V so a little over the 5V but worked for several months so seems fine (the DAC gets a little warmer though).
100% galvanic isolation from everything except the battery is nice though, no more “sounds better at night”
For MQA I let Roon do first unfold, then I upsample everything (including non-MQA) to 192khz