this link has some interesting info by some owners of upgraded 225 and DNA 2, as well as some comments by SMC.
http://forum.audiogon.com/cgi-bin/fr.pl?ramps&1114108053&read&keyw&zzmccormack=dna-225=platinum=edition=upgrades
You should also do some searches since similar topics regarding the upgrades have been discussed here and on audio asylum - amp/preamp
http://forum.audiogon.com/cgi-bin/fr.pl?ramps&1114108053&read&keyw&zzmccormack=dna-225=platinum=edition=upgrades
You should also do some searches since similar topics regarding the upgrades have been discussed here and on audio asylum - amp/preamp