[BirdManOfCT]

Would the Sennheiser HDVD800 or Violectric V281 work better with the Sennheiser HD 800 S?

 

[iDesign]

I would select the current HDVD800 over the Violectric V281. However, you should wait for the forthcoming HDVD800 which is due out October 2016. Rumors suggest the new HDVD800 will be capable of playing DSD and MQA. 
 
https://youtu.be/Z2eLgayhLGY?t=51 

 

[Mystel]

HDVD800 , since it was made and tuned specifically to work with sennheiser phones in the first place.