Sorry its been a year, I've been out, but I would like to thank you all for your excellent and thoughtful suggestions. I like the idea of bi amping, so I will look for another amp as was suggested. The castles are indeed bi-wireable and were wired so until I was convinced years ago to buy Bel wire and use jumpers. The sound improvement with Bel cable is very noticeable with more clarity and precision in piano passages and acoustic guitar. Now it has been a year since I posted this question and I have been looking once again at DAC's. There are many at this point and so it seemed likely that an improved DAC might once again be a good idea, something like the Cambridge DacMagic, for example. I also have sort of inevitably been moving in the direction of digital source, which I have listened to with iMacs hooked up to high end DACs and of course with stupidly expensive terminal gear (amps and speakers), so maybe deficiencies in source were overcome, but what I heard was really, really good. And now I have been most recently putting a lot of music (downloaded at 256 kbps) on my ipod and enjoying listening to music with some high quality Klipsch phones, and listening to music more than I have in a long time. I have to admit that I am surprised that for the most apart, my responders thought that even with over a decade in DAC improvement that a new DAC would not be more or less a no-brainer as an upgrade, especially at a price point of $4-500. So, if you all don't mind now that a year has passed, I would like to posit the same question, would a new up-to-date DAC for the 7SE be worth it?