The incremental value a $20,000 amp has over a $200 amp is $0 if you yourself can't hear it.
Having said that, I'd suggest you listen to Luxman, a close sound cousin of D'Agostino even in the integrateds, Ayre and Pass as amps that can sound different enough to you to justify the spend.
This is particularly important when selecting them to drive specific speakers as they will interact somewhat.

