[aestuo]

I just purchased a Little Dot II++ tube headphone amp, but it's getting some strange interference from my PC. Some of the other problems people have associated with this amp - ground hum, microphonic tubes - are absent, and the amp is very quiet when connected to my mp3 player, receiver, ect.

The problem is that the exact moment the Little Dot makes an electric connection with my PC, high pitched buzzing and crackling ensues. It's moderately load even with the volume turned all the way down, and gets louder as my PC gets busier. You're probably thinking this is caused by the amp sharing a ground with the PC bus, but this can't be the case. I put a wall-wart powered USB soundcard between the two, same noise. I splice and resolder both my USB cable and my phono cables to interrupt the ground wires/jacket. Same noise. I also tried a two-prong power adapter so my amp is not connected to the house's ground, as well as trying my PC's integrated sound card. Same noise. The weird part is that my PC does not give this noise off to any other amp I've connected my sound card to. And, as I've said, I don't get this noise from any other source component besides my PC. What do you think I should do?

Looking at new USB sound cards, I found this product, which brags about electrically isolating the USB signal. Would it help?
http://www.stereo-link.com/Static/1200Desc.html

Here are the offenders:

 

[GSurge]

What kind of laptop is that you're using?

 

[aestuo]

It's a Dell Inspiron.

 

[GSurge]

I've read that Dell laptops have a known problem of this kind. I'll look for some threads for you in a few minutes.

 

[penguindude]

Have you tried eliminating the grounding pin of your 3-pin plug by using a cheating plug?

 

[GSurge]

http://www.head-fi.org/forums/showthread.php?t=218868
http://www.head-fi.org/forums/showthread.php?t=238684
http://www.head-fi.org/forums/showthread.php?t=30380

I can't find the specific one I was thinking of. Oh well. The usual recommendation is to use SPDIF out...

 

[aestuo]

I tried the cheat-plug. I guess I'll buy a dac like the number cruncher and do spdif output from my external soundcard ... not an optimal solution.

 

[vcoheda]

it may be defective. i use my ld2++ all the time with my dell laptop. no problems like you describe. i would ask for a new one. ld has 30 day money back gurantee.

 

[Noobzor]

I had that problem with the 0404 DAC, what i did is run a turtle beach usb to optical, then optical to DAC. Its DEAD silent now. Im actually happy i did that, as i got my Behringer 24/96 Eq.

 

[aestuo]

Thanks everyone, I've come up with an unusual solution here. What about a passive, direct box like this?

http://www.amazon.com/Rolls-DB25-Dir...dp/B0002CZR22/

I've verified that this problem is caused by any electrical connection between my PC and the Little Dot. For example, the amp is whisper-quiet when plugged into my mp3 player - but when I dock my mp3 player to my pc (with the amp still connected only to the mp3 player), the crackling begins.

Would a transformer direct box degrade sound quality? I'd rather not go out an purchase a dac (a usb transport won't do because my dac/soundcard needs to be plugged into my pc or it mutes itself).

I guess I'll ask about the warranty as well.