I happen to be an owner of both the PWT and PWD, also the Red Wine Audio Isabellina (a DAC designed by Vinnie Rossi). Very interestingly, the synergy of the PWT with the PWD (connected via I2S with a run-of-the-mill HDMI cable) does not better the PWT paired with the Isabellina (via optical cable). In fact, the signature of the two DACs is quite similar. The PS Audio piece is slightly more detailed and "drier". The Red Wine Audio piece is characterized by (subtly) warmer, denser sound. Both are equally enjoyable.
Of note, the Isabellina costs half what the PWD does. On the other hand, the Isabellina will not handle high-definition input, and it has zero capability to become a networked music server, as will the PWD in a few months.
