If I recall correctly, the reviews for the OP2227 are that it is more laid back than the AD8620. Reviews for the 8620 sound like it is more likely to maintain the Grado signature sound, if that is what you are wanting. But I haven't heard either chip with my Alessandro MS-1i.
It is also possible that the JDS amp won't add that much to most any Grado phone, since they are all pretty easy to drive. You might want to search thru the Full Size Headphone forum for posts about how upper Grados respond to amp -- if there is any significant increase in SQ, or just mostly a volume increase.
Edited by kmhaynes - 10/30/12 at 8:33am
