How important is the transport when using a DAC?

Very much a function of the overall architecture. With reclocking and asynchronous DACs, the difference are definitely a lot smaller then with a traditional synchronous architecture. It is still a bit of a mystery to me why a transport would make any difference if the bits are fed into a buffer and then completely reclocked, but I guess they still do.

The linear powersupply in the Oppo 105 is only used for the analog section. However, some manufacturers (Ayre DX-5 - Theta Compli 3D) have put linear PSs in Oppo based players for the digital section, apparently with good results.

The ($4000) Theta Compli 3D is basically an Oppo 93 with a Theta faceplate and a linear powersupply and all the analog circuits ripped out. According to its owners it sounds quite a bit better than the Oppo 93.

I personally also have a linear powersupply in my Oppo 93, but never did an A/B comparison with the old powersupply.

One thing I learned to avoid (and dismiss if others make them) in audio is making categorical statements about the inherent superiority of one technology over another.

It is probably possible to build a fine sounding DAC using both a linear and a switching powersupply.

Steve, the best digital I have heard (by a mile) is the MSB series IV. A lot of people that have listened to every 5 figure DAC under the sun concurr. It uses a linear powersupply.

May be a better mousetrap using your switcher/series regulators is just around the corner. Who knows. Technology moves on.

For now, all I can say that if the best sounding DAC money can buy uses a linear powersupply, it is premature to write it off as technology unsuiteable for digital applications.