I've swapped out my Monarchy SM-70 Pros and will use the SDS-258 exclusively for a considerable while. Maybe a swap back the Monarchys in a month or two just to see if feel the say way.

The thing that persuades me about this Class D Audio amp is its ability to authentically reproduce the full harmonic signature of instruments, notably strings, brass, and persucussion such as cymbal. It simply beats other amps I've had in my system in this regard. It does have very sold, quick bass too, but that's not the biggy for me.

But maybe there is a price to pay: this amp is slightly on the bright side, at least in the lower treble region. To some people this would be insufferable and the CDA amps aren't an option to them. I won't argue that this brightness is truly more accurate or authentic but I will suggest that, at the very least, it doesn't detract from a highly authentic instrumental spectrum -- conceivably it's actually essential to it. Anyway, the CDA is for people who favor authenticity over sonic confection.

When I got the Monarchys to replace my previous, class D, Tripath-based Bel Canto amp, I said that Bel was the better amp with the best recordings but that the Monarchys were more enjoyable with the other 70%. Presently with the Class D Audio SDS-258 I'm reversing the ratio, i.e. that for enjoyment the CDA beats the Monarchy 70% of the time.