I am sorry for the lack of response. I don't check this very often. To clarify I have the 655 capacitors in the 600 SE so it is not a full 655 SE. I live close to BAT and they made the change for me while I waited at the factory. The midrange and high are both more open and extended than the 600. I have Vandersteen Seven speakers so the bass of the amp is not directly impacting the sound so I didn't really notice a change to the bass. I suspect other speakers you would notice a difference. For sure the upgrade was worth the investment it lets me see further into the music presentation and sounds more lifelike and real than before.
If you want to converse more you can email me at :
[email protected]