dynaudio confidence 5 , which amp is fit ?

The Audio Research REF600MkIII monoblocks sound very good on the Dynaudios. It may be a little difficult digging up the spare $40k that they cost though.

Just don't get involved too much with the numbers.Gryphon and LAMM watts are quite different,try them both.

A Suggestion: Try a Chord Pre- Power combo (Spm 1200 and up for power) Chord will certainly make a terrific match. Electrocompaniet pre and monoblocks will also be sufficient enough.
The former will deliver a more realistic, precise signal while the latter will be a bit more romantic.
One tip: avoid newer ML and Krell Amplifiers, because the result might be overly clinical. Dynaudio's are very natural sounding speakers, Krell and Levinson (334, 332, 331 etc.) will highlight this. Older series might make a wonderful match, like no.28 and no.29 combo (only 50 watts but with amazing control, unless you'll expect pa levels)

You have one of the best speaker on earth.

Among all the reasonablly priced solid state amps I have tried, McCormack DNA-2 was the best with Confidence 5. For higher price solid state, I have heard Pass X600 are wonderful match with C5. I had Pass X350 and it better Rowland 8TiHC.

The longest amp I had with the C5 was Sonic Frontiers Power 3, but I did clip them occasionally when I played loud. Tubes are magical with C5, really brings out the Esotar midrange dome, but there are not too many tube amps on earth that can push C5.