Does removing "interface jitter" help, if my source has jitter?

The Benchmark DAC 3 distortion and noise level  is -140db no need to worry about jitter induced distortion.  This is true of competently engineered modern DACs. There are even a few R2R DACs that manage to keep distortion and noise below human audibly but I wouldn't waste money on them they're overpriced. The RME ADI 2 FS is very good DAC that's cheaper than the Benchmark. 

Benchmark does not recover clock from the data.  It ignores it (asynchronous rate converter).  Benchmark specifies insane jitter tolerance of 12.75 UI bellow 3kHz and 1.5 UI above it.  At audible frequency of 10kHz jitter tolerance would be 0.1ms * 1.5 UI = 0.15ms.  That is still insane amount of jitter (0.15us typical jitter will be more likely).  Benchmark defines tolerance as "With no measurable change in performance". Perhaps we can hear what is "no measurable" but we're talking 1000x difference between typical jitter and Benchmark's tolerance.

I knew I could count on you, George…(it’s been a loooooooong time since I’ve been called sunshine).

I am thinking of upgrading my DAC3B to the Gustard X26 Pro. 

https://soundnews.net/sources/dacs/gustard-x26-pro-dac-review/

I knew I could count on you, George…(it’s been a loooooooong time since I’ve been called sunshine).

Well you were applauding and doing cartwheels like an excitable school girl, after only 12hrs and 3 posts of starting the thread up and asking the question..

Cheers George