[Joong]

I usually avoid to use USB port, which is through Gustard U12 that converts to coax for cleaning(?) the usb noise.
USB source might be widely different from to one source to another, and also dependent of cable.

 

[Ustas]

I've a question... I've recently received the SMSL M8 (after weeks of waiting) via Massdrop. Now I'm using the USB and a laptop for all my playback. The unit hasn't fully broken in yet but I'm curious...are there any differences between the sound thru USB and through coaxial? Because to me thru USB the unit sounds a little "drier" than what I'm accustomed to from my ODAC...which is rather surprising since some claim to hear more air around the instruments.

I don't own the P1 yet so all these listenings are done using the stock adapter. 

SMSL M8 has poorly isolated USB input for power and ground. The USB power going from computer to DAC is usually highly contaminated with hi-freq noise and that could be especially bad with laptops.

One solution is to use high quality USB cable with lifted ground on one end, though that may be expensive, or you may try to modify a regular USB cable like in the picture below and see if this makes any difference. You will need to isolate the pin #1 (Vcc) first and listen, then pin #4 (Ground) listen again, and vice versa.

 

[chongky]

Wow, a very detailed response. I'll try this solution when I have time. Very much appreciated! Thanks also to Joong for his response.
 
Maybe I'll first get a coaxial cable to hear if there are major differences between M8's USB and coaxial.
 
 

SMSL M8 has poorly isolated USB input for power and ground. The USB power going from computer to DAC is usually highly contaminated with hi-freq noise and that could be especially bad with laptops.

One solution is to use high quality USB cable with lifted ground on one end, though that may be expensive, or you may try to modify a regular USB cable like in the picture below and see if this makes any difference. You will need to isolate the pin #1 (Vcc) first and listen, then pin #4 (Ground) listen again, and vice versa.

 
Just curious, how much would such a high quality USB cable cost? Also, does it matter that the M8 is not powered thru USB?

 

[Ustas]

.
Just curious, how much would such a high quality USB cable cost? Also, does it matter that the M8 is not powered thru USB?

Audiophile cable manufactures may charge outrageous amounts for their USB cords. Whether there any improvements compared with quality made regular USB cable is another question.
One cable manufacturer that I trust is Wireworld they make high quality flat USB cords with separated and isolated power conductor that will outperform much more expensive "audiophile" USB cables. Short Ultraviolet 7 can be had under $60 and Starlight 7 under $100.

My and other folks experience (and also scientific research from Burr-Brown labs) shows that benefits of isolated power and ground conductors in USB cable and the length of the cord itself is the most important factors affecting sound quality.
Burr-Brown (TI) researches have found that digital jitter in USB interface increases dramatically with the length of the cord, so they recommend to keep it as short as possible. Fact is I've tested in my audio system a few audiophile USB cords costing from $80 to $350 and 6" short USB cable from Belkin ($5) outperformed them all.

In the case of SMSL M8 isolated power and ground USB cable is not required since USB power input is not active in the circuit and going the way I described in my previous post is preferable in my opinion.


BTW, the picture of the modified USB A connector is not mine - I've lifted it from another forum, on my cables I usually just pull out connector pins with needle nose pliers. (Don't try this on yours before knowing what your doing! experiment first with reversible tricks. )

 

[chongky]

Bought two cables, a cheap $3 USB cable supposed with "double noise shield conductor" and a regular coaxial cable. There definitely is a difference between music thru the stock SMSL USB cable and thru the coaxial. The coaxial sounds warmer, has better soundstage and more solid imaging. When I switched the stock SMSL USB cable with the newer one, there is a difference as well (believe I could tell them apart in a blind test). The soundstage improved, the dryness is almost gone, though the sound isn't as warm (more neutral?) than thru the coaxial.

 

[chongky]

One solution is to use high quality USB cable with lifted ground on one end, though that may be expensive, or you may try to modify a regular USB cable like in the picture below and see if this makes any difference. You will need to isolate the pin #1 (Vcc) first and listen, then pin #4 (Ground) listen again, and vice versa.

 
I'm a bit confused, since you lifted this picture. I have no background in audio science (almost a complete noob) - how do you isolate the USB pin #1 and the pin #4? Is it by applying Scotch tape as the picture stated? I did that and wasn't sure I hear a difference - though there seemed to be a tad better transparency, it might be placebo.
 
Would it be less trouble to just purchase a 6" Belkin USB cable you recommended?

 

[Ustas]

I'm a bit confused, since you lifted this picture. I have no background in audio science (almost a complete noob) - how do you isolate the USB pin #1 and the pin #4? Is it by applying Scotch tape as the picture stated? I did that and wasn't sure I hear a difference - though there seemed to be a tad better transparency, it might be placebo.

Would it be less trouble to just purchase a 6" Belkin USB cable you recommended?

I posted this picture as it clearly illustrates what pin to isolate. You did right with that Scotch tape.
If there's no difference in sound then SMSL M8 most likely omits ground and power lugs in its female USB port receptacle or they are not connected to the board. Then the cause of an inferior sound could be in the USB circuit of your laptop itself.
In S/PDIF interface digital signal undergoes two additional conversions that's why straight USB-to-USB is usually preferable given all other variables being equal. Anyways, if coaxial connection sounds better use it instead of USB.

Would it be less trouble to just purchase a 6" Belkin USB cable you recommended?

Sure, Belkin cable is very good thou for your desktop setup it may be a bit short. I know Monoprice has well built and inexpensive USB cables, just remember to use the shortest cable possible that fits your application if you'll decide to go this route...

 

[chongky]

Thanks for all the clarifications. 

 Thing is I've ripped almost all my CDs onto a hard disk and I find it a chore nowadays to search out and load physical CDs. The USB cable I bought sounds quite good. (it's the shortest I can find and 2 meters btw) I'll wait for my SMSL M8 to burn in and decide if I'm forking out another $150 for the P1.

 

[Guillaume57]

Hi, I'm new here and just bought and received the SMSL M8 after reading the glowing reports. I've hooked it up to my laptop running Windows7 and installed the driver. I'm trying to play Hi-res files through Foobar 2000 and it sounds great but everything reads 44.1kz in the front window on the M8 although Foobar says it is playing 24/96 files?
Is this a problem with the machine or am I not doing something right.
Thanks for any help and sorry if this is a dumb question.

 

[Natslx]

Set it in your device settings in windows.

 

[kazcou]

You are using Asio or Wasapi output plugin, right ?

 

[Guillaume57]

Thanks for your reply. The unit is working and I'm getting good quality sound but the unit says it is playing 44.1 kz files, while Foobar says it is playing Hi-Res files. I don't even have 44.1 files on the computer. So is Windows somehow down sampling them before they get to the M8?

 

[Guillaume57]

Thanks for your reply, I'm not sure, I installed both the asio and wasapi in Foobar but not sure if I need to do anything else besides that.

 

[hpamdr]

If you want to play through usb:
On foobar, you have to setup the Playback/Output to "ASIO:XMOS ...." on the preferences page. (CTRL+P)
 
if you want to play dsd file, you have to setup foo_dsd_asio plugin and link it to the XMOS driver....

 

[Guillaume57]

Thanks so much. I had only gone into the "SACD" flag below "Output" as I got  "pick a subtext" when clicking on other main tabs in the "preferences"-tools section..doh....
 
Anyway, it's all sorted. As soon as I clicked on the main "output" tab I saw the settings were all wrong. I put in XMOS Event  Wasapi and it showed up as 96kz in the M8 right away. Sounds great.
 
Is ASIO better than Wasapi for Windows7? Do I have to change the settings again when playing 192khz files or does Foobar handle that automatically?
 
Thanks again for your help, much appreciated.