Sony NS999ES ModWright upgrade vs. external DAC


Hi! As usual,help needed.I have Sony NS999ES CD/SACD paired with Bryston SP-1.7 Pre/Pro. What would be a better way to upgrade this combo ( I'm mainly interested in upgrading Redbook playback performance, even though SACD is important as well)?
To upgrade the CDP or to buy an external DAC?
What would be an upgrade from the Sony 999ES internal DAC and From Bryston's DAC (if not used in analog bypass mode).
My take is, that an external DAC is more flexible solution, and possibly even less expensive than ModWright upgrade. Any suggestions for DAC's in the $300-600 range used, that will be a noticable improvement over Sony and Bryston, will be greatly appreciated. Regards.
maril555
Thanks for the responses. I am very seriously leaning towards just firing my unit off to Dan when it comes in. I will see if I can swing the Aboslute Truth mod. I do not need volume control. My only concern are warranty issues. What do you do if something breaks? Sony is very nice in that they offer a 5-year warranty, but I presume that you'd be giving that up with a mod. And I also presume that Modwright would not cover things they did not do, right?

Tom.

Tom.
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Actually I ended up buying Musical Fidelity A3.24 Upsampling DAC and intent to keep it for some time. I'm very interested to compare this combo with the different levels of Modwright mods.