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Question: Want to purchase new SONY Home Theatre System

I currently own a Sony HTS (Model No.: DAV-X1V) and I would like to 'upgrade':
* what models (currently made by Sony) do you suggest?;
* should I go blu-ray or dvd (can dvds be played on blu-ray machines)?;
* I have a Bravia flat panel that I'm NOT upgrading;
* first and foremost, I want more 'power' with my new HTS, i.e., more audio-related power (say higher volume levels, clearer sound, etc.) than the DAVX1V model.