The DNA-2 is somewhat different from the other DNA amps in that it was designed by Dave Reich from Theta Digital.
The DNA-2
uses a dual mono, true stereo topology, while McCormack's other monster stereo amp, the DNA-500, and their converted
DNA-0.5 and DNA 1.0
monoblocks, are
differential/balanced amplifiers where two complete amplifier sections drive each channel. While there are advantages to both topologies, the dual mono, true stereo topology allows the DNA-2 to provide a tremendous amount of current, up to 100 amps, as indicated in the manual
here.
Regarding the input board issue discussed by
@soix, I would recommend discussing that with Steve McCormack at SMc Audio since there are many of those DNA-0.5 and DNA-1 amplifiers still in service. While I have no idea what might cause board failures or the incident rate, I do know Steve can take your DNA-0.5 and rebuild it into an amplifier that far surpasses the original and that can compete with most anything out there. He uses completely new, redesigned boards for the 0.5 and 1.0 rebuilds/upgrades so the condition of the original boards doesn't matter. With the DNA-0.5 in particular, because there is additional room in the case, he typically increases the size and quality of the transformer to increase the current capability of the upgraded amplifier over the original. You may be able to simply upgrade your existing DNA-0.5 amplifier and have both better sound and a higher current delivery capacity plus the ability to obtain a second DNA-0.5 in the future that SMc could upgrade and then convert both amplifiers to monoblocks.
Here is the SMc Audio website. You should look at the "Video interview with Steve" - Part 3, which shows an example of the upgrades. Call Steve.