Asynchronous .. or not asynchronous !!

[Vinyleyes]

Ok this has been burning this digital numbskull now for some time now ... :doh: ... I want to play music from a computer ... all different levels of quality .. from 192kbs MP3's through to full lossless/Flac and CD rips and Internet radio .. . I have seen a plethora of USB/PDIF convertors from a few pounds to a few hundred pounds .. and then there is the DAC to buy .... but what I do not understand is this need for asynchronous feed from computer to DAC ... I am not bothered to know the technical reasons .. I just want to know what configuration I need to get the best sound. So .. do I need to invest in this USB/PDIF convertor .. or what is wrong with a simple DAC that has a USB input ... or should the DAC then be asynchronous !! there are not too many of them around .. but loads of USB/PDIF convertors .. and when I talk about convertors I am assuming that we need them because they give an asynchronous feed into the DAC ..... and not just because we may be using a DAC without a USB input.

So for my 100th post to this great forum .... a big thanks to all who have given their advice to me so far and it has been nice to meet you all here ..... BUT ......... pleeeese ... put me out of my misery on this one ... :)

:cool:

[jantheman]

but what I do not understand is this need for asynchronous feed from computer to DAC ...
:cool:

No need at all...some say async is best others say different....listen (if poss) and decide for yourself.

[purite audio]

'ordinary' USB carries the data and timing signal, as does s/pdif and Aes/SBU , with Async protocols the DAC clock is in sole control of the flow of data, technically ( provided everything is designed and implemented properly) it is the best method of transferring timed data.
In my experience it is better to use an Async DAC ( FireWire or USB ) directly into your PC/Mac than to add another layer of conversion ,ie a USB to S/pdif converter.
Try and borrow a few dacs and compare them in your system, if you need any help with any aspect just give me a ring.
Keith.

[Vincent Kars]

Almost all USB audio uses adaptive mode.
The timing is derived from the incoming data stream.
You can compare it with a transport and a DAC connected using SPDIF
The DAC adapt itself to the timing of the transport

Asynchronous USB, the DAC times the data out of the PC
This allows for a fixed clock.
You can compare it with a traditional DAC with a clock out to the transport.

Asynchronous is said to have lower jitter than adaptive.
A lot of new products have asynchronous USB

Do you plan to play hirez ( 24 bit and/or sample rate > 44.1 )?
If so be careful as a lot of USB DACs are limited to 16/48 (cheap drop-in chip)

Do you have a DAC? If so you might look for a usb/spdif converter.
If not you better look for a DAC with USB input.

Of course, the protocol (adaptive or async) is not the only aspect.

A list of USB DACs xan be found here: http://www.thewelltemperedcomputer.com/HW/USB_DAC.htm
Converters: http://www.thewelltemperedcomputer.com/HW/USB_SPDIF.htm
Some background: http://www.thewelltemperedcomputer.com/KB/USB.html

[Welder]

If you’re going for file-computer-USB then I think asynchronous is the way to go.

Strangely enough, the best Dac I’ve heard wasn’t asynchronous but you would have to build it.

I would avoid the SPDIF converters in general, the Halidi Design Bridge being a possible exception. Converters just add expense and complexity to the audio chain.

Most of the good Dacs I’ve heard have USB asynchronous and other connection options.
I decide at the point I transferred from vinyl to file that I didn’t want to be messing about with SPDIF, or CD players and asynchronous USB seemed at the time to have the greatest possibilities for the future.
I haven’t regretted the decision yet, but USB in general isn’t without its problems, particularly with regard to power supply (a bit in my gallery post about USB power)

Imo it’s still a bit of a struggle to get file audio bit perfect. It’s not quite as straightforward as some would have you believe if you wish to play any resolution audio.