I had Mscaler and Dave both with SJ Power supply, before moving to Lampi Pacific and then Horizon. I would get that second power supply. And the Wavestorm interconnects between the mscaler and Dave if you dont have them already and grounding for all 4 units.
Yes, The Wave High Fidelity STORM digital BNC interconnect cables make a BIG difference with the Chord DAVE and Chord M Scaler. So much so, I would say they are a MUST for DAVE & M Scaler.
They were specifically designed and built for the Chord Blu, Chord DAVE and Chord M Scaler !
And Nick Bacon is a great guy to do business with to (he is only an hour's drive from my base in the UK).
And as you have already got a Sean Jacobs ARC6 DC4 ELPS for your DAVE, I would get the same for your M Scaler.
Then with the STORM digital cables you have a top notch digital source for only the cost of another Sean Jacobs ELPS (should be cheaper for the M Scaler than the DAVE) and the cost of the STORM cables !
Chinese whispers last year or so are saying that a new Chord M Scaler will be coming out maybe this year (possibly for the Choral line) that hopefully will take the Chord DAVE set-up to another level !