what more do u want to hear out of your current "sound"?
i think the pandora does quite well out of humble setups,
but there will be improvements in clarity, separtation, depth etc but in decreasing return$$.
i am listening to youtube musical vids on the pandora straight off my McAIr..
and was enjoying it until i saw your post,
decided to plug in my Audiogd dac amp,,,
there is an immediate improvement in clarity space depth.. definitely CLEARer.
but is it worth $600 more...u have to decide
anyway....do pick up a desktop dac/amp if u can spare the cash
your other/future cans will benefit too.
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edit...your sony is a $500 AMP...? what dac are u using now..
maybe u should invest in a "better" dac?