Fiscally speaking you'd be best to sell the DNA 0.5's and buy another used amps. I agree with most of the reco's here, I haven't heard the Musical Fidelity. I also agree with hifiguy, I have a Threshold T400 which I like better than the McCormack IMS. McCormack is a nice SS amp, but to spend $1800 upgrading it, you would never recoup that money if you decide in another year or so. I'd sell and go with the more expensive McCormack's (if you like that sonic signature) or a GamuT, Classe, Threshold or Rowland, IMHO.
Amp upgrade recommendations
I am considering having a pair of DNA 0.5s upgraded to Rev A and converted to monoblocks to run balanced off of my BAT VK3i, which is driven by a CAL CL-10/Classe' DAC also running balanced. Speakers are Vandersteen 3Asigs. Or I could sell the amps and buy something else. The mono-block conversion and upgrade is $1800; amps would yield about $1400-1500.00 (one is already Rev B) if I sold them. Any thoughts on which route might be better? I do not want to get involved with a tube power amp. Thanks for your ideas.