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The Moog
2009-10-26, 05:26
Hello all,

I have been running my trust SB3 via the S/PDIF into an external DAC now for a good while and have been reasonably happy with the sound, but have been interested to hear about the improvements in the Touch's digital outputs (thinking that it might be worth the upgrade for this alone).

While pondering this, I remembered that my DAC has a USB input and therefore wanted to know whether it was possible to bypass the nastiness of the S/PDIF interface all together, and push data from the Touch to the DAC via USB (and if this would be a further improvement over the improved S/PDIF)?

Cheers,


The Moog

JohnSwenson
2009-10-26, 16:30
Yes you can plug a USB DAC into the touch's USB port. Unfortunately the player doesn't know its there so it doesn't send any music to it. I'm working on an applet that will let you select the USB DAC. I hope to have it working by the time you can get a touch in your hands.

Will it sound better? There is no definitive answer. Both the S/PDIF out and the USB port are very good, so good implementations of either type of interface will do well. So its really about the implementation of the S/PDIF and USB receivers in your DAC. There is no way to tell without really listening.

In many devices the USB was added as an afterthought by using a cheap USB receiver chip sending S/PDIF to the S/PDIF receiver so the signal goes through BOTH (can you say worst of both worlds). In these boxes going to S/PDIF will probably sound better.

There are others where the designers have done a very good job on the USB implementation which can sound better than the S/PDIF input.

There are far more of the first type than the second type so without knowing anything about your DAC the probability is that the S/PDIf is going to sound better, but it may not.

John S.

The Moog
2009-10-27, 02:24
Thanks for the reply,

It is good to know that you will have the option of using either, and can therefore switch between them on the DAC to hear which you prefer.


The Moog

Themis
2009-10-28, 04:06
I'm working on an applet that will let you select the USB DAC. I hope to have it working by the time you can get a touch in your hands.
This is excellent news John !!!
Thank you for this, I'll be happy to install it as soon as it's ready. :)

Peter Stockwell
2009-11-03, 06:40
It would be very nice if one of those HRT Music streamers could be used on the usb port of a touch.

Even nicer if you could use a usb hub and have a HDD and an usb dac attached.

JohnSwenson
2009-11-03, 21:00
You CAN run a USB DAC over a USB hub, I have done it. I have also run the USB DAC AND a USB drive on the hub using the internal server. It does WORK but the sound quality suffers.

So whether you run off the internal server or over a network depends on how much of an audiophile you are and how much you value the internal server capability.

A good USB DAC used with a networked server sounds very good, its not quite as good with the internal server. (its not so much the hub, but the extra load on the processor)

John S.

funkstar
2009-11-04, 03:00
A good USB DAC used with a networked server sounds very good, its not quite as good with the internal server. (its not so much the hub, but the extra load on the processor)
Really?

I would be interested to hear if you got the same result when using an SD card as the source for TinySC as opposed to USB through a hub.

JohnSwenson
2009-11-04, 10:21
I'm pretty sure its the server load rather than both drive and DAC on the USB port because I can here the same degradation on the analog outs as well.

Lest anyone get the wrong impression I'm not talking about the sound being broken or bad in any sense, its just that from the networked server the sound is spectacular and not quite so spectacular coming from the internal server.

I have not tried the SD card yet, that will be an interesting test, but I can't run it right now since I can't get TinySC to work currently.

John S.

jacobdp
2009-11-12, 18:13
I'm pretty sure its the server load rather than both drive and DAC on the USB port because I can here the same degradation on the analog outs as well.

Lest anyone get the wrong impression I'm not talking about the sound being broken or bad in any sense, its just that from the networked server the sound is spectacular and not quite so spectacular coming from the internal server.

Presumably this is because the increased load affects the quality of the internal clock generation. Have you checked that internal vs. external server choice doesn't affect the sound if you're using an async USB DAC?

JohnSwenson
2009-11-12, 19:18
I do have a an async USB DAC, but I don't remember if I checked the network VS local server with it. I DO have tiny SC up and running again so I can test it. (the problem was they changed the format of the database file and I had an old one on disk, it read that file, came up with an error and quit. I deleted the file, it rescanned and was fine from then on).

One interesting tidbit with async is that I recently found out that the ALSA version currently in the Touch does not correctly implement async USB. The developers have seemed willing to put in the latest version, but I don't think its in there yet. So using an async DAC may not be the best test at the moment.

John S.

Hamnberj
2009-11-13, 04:31
Would be fantastic if it would work to attach to the Nuforce Icon amp directly through USB.
I beleive it would be a killer combination!

/J

georgeh
2010-03-13, 16:50
Hey John, did you ever make any progress on this? Were you able to verify support for asynch operation?

I find myself liking the idea of a networked Touch driving a dB Audio Labs Tranquility dac via USB.

JohnSwenson
2010-03-13, 17:19
I do have a firmware that supports async USB correctly but it didn't make it in before the code freeze so its not going to be in the initial release. I had to hack in the latest ALSA driver into the older ALSA version used in the Touch. I finally got it up and running and working very well, but it was too late.

I'm not sure how Logitech feels about letting others have a non official Logitech blessed firmware. Its only recently that they have made the sources for firmware for some players available so I don't think its come up yet. I'll have to ask and see what they say.

John S.

DaveKen
2010-03-14, 04:56
Hi John,
I would be interested in this, as I suspect would be a nuber of my friends on other fora. A few of us have Beresford DACs with USB inputs so we would all be tentatively interested in this facility, if it was to become available.
Please keep us in mind :-) .
Dave.

pounce
2010-04-25, 21:11
John,

I posted a duplicate thread because I didn't see this one. How is this coming along?

I'd be interested in getting a Dacport working with the Touch:

http://centrance.com/products/dacport/

I also have an iBasso D10 to play with if you need some testers.