I have had almost exactly the same problem with my recording setup. I 
got a background whine when using my Toshiba 650 laptop on mains but 
much less on my Dell D600. Both connect through a Behringer 202 DAC to 
my amplifier and turntable. The problem manifests in both Linux Mint 
(now running 13) and Windows XP. I solved it in part by moving the earth 
strap on the turntable to another point in the system - actually a 13 
amp plug in the wall! It made no sense since an earth loop should be 
much lower in frequency(?) but it worked for me. It also made a 
difference if the DAC was only connected for input to the laptop rather 
than both input/output.
If any of this helps I'd be very interested.
Nigel Long
On 25/06/12 08:30, Sean Gibbins wrote:
> Morning All!
>
> This is an interesting issue that has recently reared its ugly head 
> again in a slightly different form.
>
> Originally it manifested on my Toshiba NB200 running Xubuntu 11.04 
> through to 12.04 (and may have been present with Puppy LInux on the 
> same hardware - I can't remember if that was the case now, but suspect 
> it was*).
>
> The setup was as follows: the NB200 was connected to my NAD PP-3 phono 
> amplifier via USB in order to receive a signal from my record deck, 
> which I would record using Audacity picking up the PP-3 as the input 
> source (I often rip my vinyl purchases so that I can listen to them on 
> my portable media player).
>
> When the NB200 was connected to the mains via its charger a very 
> audible high-pitched whine would be introduced to the recording. 
> However, by doing the recording on battery power and the whine 
> disappeared. At the time I put it down to a badly shielded PSU made do 
> with the workaround.
>
> Fast-forward to this weekend when I got it into my head to download 
> Audacity on my Mac MIni running OS X 10.6.8. I hooked it up to the NAD 
> PP-3 and ripped a new album only to find that the issue exists with 
> this hardware set-up too.
>
> Obviously the original workaround does not apply since the Mini has no 
> battery to fall back on, but it got me to thinking: why is this 
> problem manifesting at all? Surely the output from the PP3 is a 
> digital signal and therefore immune to electrical interference - or 
> put another way - where is the whine being introduced into the signal?
>
> I guess I am stuck with the workaround for the time being, but it 
> would be nice to understand what is at work here, if anybody can assist.
>
> Sean
>
> * it definitely did not manifest on Puppy running on my old Dell work 
> laptop on mains power
>
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