AppleTv: high frequency audio issue

Hi,

I think i pointed out an tricky issue on the AppleTv.

There is an big issue in the high frequency restitution while i play a sound from my iPad through my AppleTv with Airplay.

For instance there is no piano while i play "While my guitar gently weeps" from the Beatles or they is no second guitar at the beginning of "Sometime" from Pearl Jam. This is a huge problem!

I am absolutely sure that the is because of the AppleTv because i have done several tests to isolate the issue.

I have tested:

- with an audioCD, playback is ok. So my speakers and amplification are ok.

- Playback is ok when i use a french Internet Box, so this not coming from the WiFi nor the low quality mp3 nor my iPad nor my Tv (speakers are going to the amplification through my tv).

- iPad are not in cause because it is the same with my iPhone or Mac and it is working well with another box.

- Playback is good with the speaker of my iPad.

At the end, it could be the Apple Tv (software is updated) or maybe the way Airplay is done by Apple.

I really need to tackle this issue! Thanks for any help you could provide.