Upgrade McCormack or...

I had a DNA1 and not for a million dollars would I risk swapping it out for a Mac. You can take a pass on the unsound advice above. 

Sorry, but

Send it in to have Steve work his magic. No regrets.

I see it has almost been two years since my post four down.  I am still enjoying the SMc/McCormack Ultra-G DNA-1 monoblocks.  They are the closest I have come to amps that display an adequate combination of tone, dynamics, detail, staging and power, without noticable faults.  They do a great job of driving my speakers and sound very good with whatever music I play though them.

To the question asked back then by @cheeg , the Clayton M300 monos were outstanding at portraying a realistic tone and dimensionality that was reminiscent of live music, and while I enjoyed them for years their Achilles heel IMO was that they seemed to fall just short of providing adequate dynamics for rock music, at least with my speakers.  They were certainly powerful enough but just missed having that speed or urgency that rock music needs to come alive. 

Back to the DNA-1s and the question by @djsrubin - I am not sure what would cause an "intermittent power switch issue" but if you have done any DIY at all, you should be able to work with Steve and rewire a new switch on your amp yourself, assuming that is in fact the problem.  If you send the amp to Steve, the sweet spot would be to have him perform a full upgrade using the new boards.  I believe the whole thing has to come apart to install the gravity base so a full upgrade would seem practical if you can afford it.  If you don't have the Plitron transformer, that would also be a worthwhile upgrade IMO, although I heard he may be sourcing his low-noise toroidal transformers from another manufacturer now because of a Plitron availability issue.  I  suggest talking to Steve about options and costs because the end result would be well worth it IMO.

@millercarbon +1

@mitch2 +1

I had my DNA-1 upgraded two years ago, and wouldn't trade it for anything.  Mitch2, thanks for your response on the Clayton monos (better late than never) -- as you can see, I stuck with McCormack and have been very glad I did.  Also, I agree with your advice to djsrubin re working with Steve.  He is a rare find, and gives wonderful customer support. 

@cheeg - I am glad to hear things worked out for you, but after working with Steve and Patrick for years, I am not surprised.

Ignore his advice, take mine instead, even if it's the same. Sigh.