Hey JohnJohm,

There appears to be no solution to this problem as posted.   I spent a lot of time with Dell on this.   The bottom line went something like this......

• XP design, development and significant support releases preceeded HDMI
• Because HDMI integrates audio and video (and probably because of a lot of other security and copyright BS) it requires support of not only the audio (IDT) driver but also the video (Nvidia) driver, plus the OS (XP) all the way down to the BIOS.
• I lot has been learned about the issues with HDMI and all the interractions between these parts over the insuing years and even to this day they are still making changes even down to the BOIS level of computers to handle HDMI properly.
• These changes necessary to take advantage of the learnings and improvements are no longer being made to XP
• Not suprizing, at the driver level, the changes are not being made to XP (audio and video) drivers to fix things either,
• In fact it appear the IDT audio driver for XP doesn't work properly at all with HDMI and doesn't even appear to support HDMI.
• The Nvidia driver is a little better.  They at least made an attempt to support HDMI (including sound) at some point and for the "most" part it works.  However, there are features you would expect there also that seem to be missing, plus it links back to the broken IDT driver....  
• Upon further research I learned that the Nvidia driver that Dell uses for XP on the E6520 was not written for the video chipset used in the E6520.   It is a generic driver from a long time ago (2008?).  If you go to the Nvidia site, they do not have an XP driver for this chipset.  They reference the old generic one.   So, perhaps this is not entirely Dell's fault.....  Its a question of where you think the buck should stop..... Dell... Nvidia....Microsoft....
• The bottom line comes back to the fact that XP predated HDMI and Microsoft will never bring it up to date to support it completely... so no one else worries about fixing the problems (Nvidia, IDT, Dell) and who can blame them.  XP is two generation old.  Technology marches on.... Windows 7 is where its at.
• Hence the so so support of HDMI when using XP on the E6520.  

OK..... so much for the bad news.   Here is the good news.  If you follow the practices below, sound will work.  You may not have all the fancy sound settings and features you when you use Windows 7, but it works.

• Understand upfront that the computers control panels (Volume Control, Sound Control Panel and Video Control Panels) change their features and options depending on whether an HDMI device is attached and turned on or not.   Don't be confused by this.  I was.  Don't look for things you saw when the cable was detached or TV turned off that you saw when it was connected and on.
• With HDMI cable detached, click on the speaker icon in the task bar and under Volume Control panel Options/Properties settings you see the mixer device it is set to IDT Sound with no other choice.  That's fine.  That's how it looks when HDMI is not connected.  Close the sound control panel.
• Connect the HDMI cable to a monitor/TV and turn it on and you should hear the sound of the computer recognizing the HDMI connection/monitor.  This should cause the sound driver to switch to Nvidia (and control panel options will change too).  Verify this by clicking on the speaker icon in the task bar again and under the Volume Control panel Options/Properties settings note you should see multiple devices now all set to Nvidia with IDT Sound as a second choice.  Leave it set to nVidia.  That's good.  If the playback device isn't set to Nvidia it is a problem.  You may be able to change it to Nvidia here, but to get it to stick, you may have to go to the main Control Panel and open the Nvidia Control Panal and set the Sound  Device to Nvida there.  Note that you can only see the Nvidia sound device options when the HDMI cable is attached and the monitor/TV is on.
• With this done, sound will always work with XP and HDMI if do things in the following order....

• Reboot your computer
• Turn on your TV/monitor (and don't cycle its power later, it is the same as disconnecting a reconnecting the cable later)
• Connect the HDMI (very important this be done before opening the browser or video player and trying to play a video)
• Open your browser or video player
• Start the video
• Do not cycle power on your monitor.  If you do (or it times out and shuts off by itself) you need to at least shut down the video play or browser and turn the monitor back on with the HDMI cable connected before you fire up the browser or video player and start the video.

• If you made the mistake of starting the video with sound before the other steps..... forget it.... too late... you won't get the sound through HDMI.  Start over.... You may not have to go back and reboot, but sometimes I had to.
• Windows 7 has full support of HDMI by all the players.   If you can use it, do.   You will get a lot more options for HDMI sound settings and can set the HDMI as the default output for sound.

As for the IDT driver under XP supporting sound or working right..... it appears hopeless.... at least from everything I found.

I hope this all helps.....  

Peter

     

Oh... one more side note..... it is not related to sound, but is related to the Nvidia drivers......  I hope I can remember all this accurately, but if not it is close....

If you ever run into the problem where you lose color to your TV/monitor (it goes Black and White on you) .....  don't worry.... there is a rational (albeit somewhat complicated and frustrating) explanation.   Here goes...

• There are profile "files" kept on your PC by the Nvidia HDMI video driver (and all video drivers I suspect).   These have something to do with recording your brightness, contrast, color etc settings you set up for your laptop display and external monitors.
• Nvidia came up with a setting in their video drivers they call Digital Vibrance. Its like a color intensity setting.  You can find it under the main Control Panel, Nvidia Control Panel, Adjust Desktop Color Settings of any laptop.  It is one of the slider bars.   It exists similarly for external monitor settings.
• Apparently orginally Nvidia defined Digital Vibrance to be something you could only add to (from the default).  So the default setting was 0 out of 100 with the slider bar all the way to the left.
• At some point Nvidia decided that Digital Vibrance should be something you should be able to add to "or subtract" from the default.   They then redefined the default (normal) setting to be 50, or the the slider bar midway between 0 and 100.  You could now lower the Digital Vibrance too.
• Well somewhere something gets screwed up in the initiation of the profile Files.  Its rare but it happens. There is a situation where the profile file can get reset and if it does it gets reset to to the original defined default value of "0" for Digital Vibrance instead of the new default of 50.   Under the new Nvidia driver rules, a Digital Vibrance setting of "0" is the equivalent to no color at all, or Black & White!
• So if this condition happens to occur, where the file gets reset improperly, suddenly your TV or monitor will go Black and White when you use it with HDMI.  No amount of messing with the monitor's hardware settings will fix it because the signal it is receiving has no color in it.   I even saw a very bizarre occurance (for which I still can't explain), where first only one of four HDMI ports on the TV exhibited this behavour when connected to my laptop, then three of four HDMI ports went Black and White.  I was sure the problem was the TV.  This could only be explained if there were different profile "files" kept for each "port" of a device, some of which get reset to "0" digital vibrance and others that do not.   All my research indicated this is not the case though, that only one profile exists per hardware device.  But it happened.   So if you see this even stranger event..... you are not the first.   
• Anyway.....  to fix the problem just go in and move the Digital Vinbrance slider for your monitor in the Nvidia Control Panel and slide it to 50.... and wa la....  no more black and white.

I mention this in this thread because it is another quirk of the the same Nvidial HDMI driver.......   one I suspect will never get fixed due to the age of the driver.  But it is still being shipped in Dell computers today with XP.

Good luck my friends....

Peter Van......