First of all, has your Ack! DAC been broken in (~300 hrs or 400-500 hrs with the high res cap). I have owned the previous iteration of the Ack, and loss of high freq extension is inherent in its design. Although the 2.0 is suppose to fix from of problems of the previous generation, it is still a NOS filterless design and you can't fully get away from this problem. The thin sound may also be due to lack of break-in.
In the 500 range, the Pioneer CD or DVD players in this range have pretty good transports with good transports. The Panasonic DVD players seemed OK but I don't trust the reliabilty. The Denon universals suppose to have good transports but I have read reliability problems as well. I didn't try to buy used transports becuase of reliablity issues as well. The Onix CDP have a reliable transfort for $300. I would really stay away from the Toshiba, my 2 samples made unacceptible noise/vibrations. You're kinda stuck at this price range.
In the 500 range, the Pioneer CD or DVD players in this range have pretty good transports with good transports. The Panasonic DVD players seemed OK but I don't trust the reliabilty. The Denon universals suppose to have good transports but I have read reliability problems as well. I didn't try to buy used transports becuase of reliablity issues as well. The Onix CDP have a reliable transfort for $300. I would really stay away from the Toshiba, my 2 samples made unacceptible noise/vibrations. You're kinda stuck at this price range.