it's true that my dmp-z1 can't drive the ab1266 phi to his full potential, tried it via the balanced port on normal and high. was a surprise for me because with the diana phi it's a perfekt match. even if the big abyss needs only a bit more power as the diana phi it hits the border of the dmp-z1 (power delivery/control).
as good as the diana phi pairing are the obrave ra c together with the dmp-z1. i have no other pairing for the obravo thats sounds so good.
both the diana phi and obravo are quite neutral/natural/linear sounding headgear, a fine match for the dmp-z1 who has a warmer tonal character whitout loosing details. the dmp-z1 reminds to the great nice sounding sony amps some decades ago, it's great that sony didn't forget this dna, the wm-z1 was the first product since years which had this fine character again (but not as refinded as the dmp-z1).
it's also true for me that i prefer the dmp-z1 over the chord products, imo they are not primary technical inferior but lacks the refinement in the tonal signature for me (which the dave is fine vs the overall brut hugo 2). i would not be suprised if they measure (a lot) better but i miss the fine touch in the tonal signature. that's the hard part, it's nothing that you can be measured but needs a lot of time testing different transistors, resistors, parts etc to finde a fine match.
the sony dmp-z1 is beaten by my big desktop gear but not by much, for me it's a dap/amp that competes easy with gear in the 10k price range. but it's also a product for someone who can value that a technical gear can have a quality of a fine violin and thus have a own character that shapes the music you play.
imo i think this is the big divider whithin the audiphile communicty, is it's ok that the gear you are using shapes the sound you play?
at the end it's your decision - as long you get goosebumps your on the right track
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