How good of a DAC is the Logitech Transporter

I believe a USB solution would still ultimately involve an S/PDIF conversion operation - and thus there would be no reason to use USB with a Transporter. A main feature of these SlimDevices units is to avoid any such S/PDIF conversions - the network connection avoids S/PDIF and gives an optimum connection medium.

Also, regarding whether there are "better" AKM dac chips available, keep in mind that Sean Adams (designer of the Transporter) implemented the chosen AKM dac chip in a very optimized way. Here's a quote-snip from him:

Sean Adams: "However, in the case of Transporter there is a very large improvement over the manufacturer's specs because we are using the chip in a far more advanced design than AKM's evaluation board. For the THD+N figures this is especially due to the jung regs and the selection of certain passives in the amps/filters. The clocks are very important too, but this isn't meaningfully reflected in THD+N tests."

I've been evaluating the Hiface USB to S/PDIF from M2Tech. With my asynchronous DAC, the Hiface considerably outperforms my Transporter (both upgraded or stock). The Hiface was connected to my Sony VGN-SZxxx Sony Laptop streaming wirelessly audio files from the same server used by the Transporter. Player is Foobar with KS plug-in.

As for the DAC/Analog stage of the Transporter, it is the same as in the AK4396 datasheet recommended circuit for balanced + single ended output (page 35, fig 17). As you can see, there are coupling capacitors at the DAC outputs and NJM5534D Op Amps.

"However, in the case of Transporter there is a very large improvement over the manufacturer's specs because we are using the chip in a far more advanced design than AKM's evaluation board."

I think I'll point AKMs attention to this statement. :-)

Best,

Alex Peychev
www.aplhifi.com

Alex, your Hiface/DAC outperforms the Transporter, maybe because your DAC is simply better but not because Hiface USB-S/PDIF is better than network?

Fiface is more a convenience device instead of an enhancement, right? if i stream wirelessly (or via ethernet) from my laptop to the Transporter, then i don't think using an USB-S/PDIF would improve over network, right?

Raymond, I am evaluating Transporter and Hiface as "digital transports" with my DAC using S/PDIF connection (I am not interested in the Transporter DAC/Analog section). So, I wouldn't say that Hiface is just a convenience and, unlike Transporter, it is 192KHz/24bit capable.

Best,
Alex Peychev

Alex, i see...

I know the Transporter is only capable of 24/96 natively, will it make it 24/192 by simply adding a Hiface interface? i mean, ultimately you will need to use the Transporter's digital out to go into your DAC, is that digital out 24/192 or 24/96? i am interested in your experiment, let us know your findings please :).

best regards
raymond