Gremlins Emerge with Switch to Windows 7

CW,
Make sure you are bypassing the internal windows mixer. SPDIF settings should not be coming into play when using USB output. In another current thread (near the end of it) here somebody posted a link to the dCS "cookbook" for setting up computers (MAC and windows) software to get "bit perfect" output. Reading a file, converting to PCM and sending the bit stream to USB port is a simple task that requires little resources. You just have to make sure that software stays out of the way as much as possible and not tamper with the bits.

since this is a laptop its likely that you are only willing to go so far, i.e. you have to strike a compromise between a dedicated server and a multitasking machine. The biggest degradation to audio transparency is (a) the audio hardware limitations (b) the jitter introduced by cycle stealing between computer processes... your audio card may have practically no jitter in a test lab situation but in a real life PC that doesn't happen without tweaking.

1) run your laptop off outlet power

2) setup a custom power configuration with all hibernate/sleep/idle options disabled... anytime the machine has to rouse hardware(video/CPU/HD/USB) from a power saving state it introduces audio degradation

3) if your BIOS has power saving options, note the defaults and disable (video/C1E) when playing music. Restore when on battery or your battery life will suffer

4) analog laptop sound card output is usually not great. Use ASIO if your only choice is analog out. Otherewise try to use digital to an external DAC. Kernel streaming is actually better than ASIO but can be more challenging to get working without stutters and dropouts

5) get DPC latency checker from Syscon. try to get your latency below 300 microseconds

6) once you have your latency cleaned up disable all audio buffering in your playback program or put to the minimums possible. I find that when I increase the buffers beyond the minimum for the output mode, the stereo image collapses.

CW, here's the link I was talking about: http://www.dcsltd.co.uk/page/assets/dCS_Guide_to_Computer_Audio.pdf.

Sorry, link was mangled. Try this: http://www.dcsltd.co.uk/page/assets/dCS_Guide_to_Computer_Audio.pdf

Al and Davide really helped to solve the puzzle.

As mentioned above, I thought a simple reboot addressed much of the problem, but I finally had time this week to remember and take a closer look at the power and "sleep" settings.

Wow - that made a huge difference and really seems to have eliminated the problem.

Why computers would automatically do that with such bad side effects on performance without disclaiming them makes me crazy.

Why not set a machine for proper performance, and then be able to choose maximum battery life, while understanding that certain functions may suffer?

(But then again, I suppose most of the world thinks MP3 and iPod earbuds sound good.)

Later, I hope to spend more time with the geekier aspects of configuring PCs for audio as described in the DCS article.

IN the meantime, worrying about jitter, RFI and outlet power before changing the sleep settings, was a bit like wondering if I was using the right amount of spice when there was a dead rat in my soup.

Thank you all for expert advice as usual.