RFI Noise/Hiss with 2011 Legacy Limited Kenwood with Nav + HK amp/speakers

I purchased a 2011 Legacy Limited a few months ago. It has the Kenwood OEM head unit with nav + the Harman Kardon amp/speakers.

I didn't realize until after the purchase that the system emits some kind of RFI around 6.5khz. This isn't the normal noise floor deal. This is something on top of the noise floor. Also the amp was pumping at low volumes because of variable gain.

I contacted HK and one of the engineers responded, offering to replace the amp. They shipped one immediately. The gate time was much longer, and that completely eliminated the pumping issue.

NOTE: The engineer at HK has been great. They have provided excellent customer service. They really are trying.

However, what I presume to be RFI remains. So I guess this means that either a) there is a poorly placed cable (near some source of RFI) or b) there is a problem with the Kenwood OEM head unit.

Anyone else with this problem?

Not a stupid question at all! No noise at 0. And again, the 'noise' isn't the normal noise floor that almost all of those systems produce. I swear I think this is coming from the display or some other source of EFI.

Curious you should mention the display. There is an option to turn it off temporarily, but I still hear the noise, even when off. But I'm going to go play with the display brightness.

Now I need to ask a question. What's the VFD?

(and thanks for taking the time to read/respond!)

Vacuum Fluorescent Display

As for your noise - I'm guesing it's the head unit. If Subaru is still using speaker level outs to the H/K amp, it's highly unlikely the wiring is picking up any electrical noise.

Is it RPM dependant? Present when running the radio from the battery with the engine off?

Gotcha. The display is LED. I think.

I believe these are line level inputs on the amp. I can check with HK.

This is not RPM dependent. It centers around 6.5k. I have a recording of it, but not sure where to post it.

That was with the engine off, eh? Interesting.

I'm assuming it does it with any audio source, FM, AM, CD, etc..?

Follow these steps to make a silent CD: http://legacygt.com/forums/showpost.php?p=379369&postcount=381 and play it back so we can get a better sampling of the sound.

It's all just experimental at this point. Short of having the head unit replaced (still under warranty?) I don't know what would fix it.