How to add Dolby Pro Logic II support?

I have a Rotel RSX-972 and am very happy with it.
It has the usual pre-outs and also 5.1 inputs.
Currently I feed my Sony 999ES to the 5.1 inputs for SACD.

I would like to know if there is anything, that is just a simple decoder/processor, budget price, that will let me add Dolby Pro Logic II. I am just curious how much it would improve watching TV, so I don't want to spend a lot of money on it as I am not ready to upgrade to a new reciever yet. But I cannot seem to find such a device.

I've seen the Processor/PreAmp components, but I don't know if such a component would work or how, as both my receiver and the preamp would have their own volume controls. Plus I don't think you can get anything half decent processor/preamp for less the $500.

Thanks in advance,

-- Sanjay
Yamaha RX-V1400 receiver, which can be used as pre/pro, has DPL II for less than $600 (Internet). One can bought at Good Guys or Circuit City for $799 MSRP. Personally I have it and tested only once. Never bother to use DPL II again. I often listen to 2-channel stereo, DD & DTS, or 7-channel stereo, depending on media. Volvo offers DPLII in its SUV, but I've never tried it. I don't think that I'd like it personally.
It appears the Dolby PLII is mainly meant for improving PL's music performance and not so much for Movies or TV. Nice to have if you are buying a new processor, but not worth upgrading to on its own.

"Introduced last year, Dolby Pro Logic II is an improved, more intelligent matrix decoder. So improved is its decoding, that it succeeds where Pro Logic performed poorly, i.e., playback of non-encoded material such as conventional 2-channel music. That's not to say it is a music-only application, but it certainly makes for a new and wide appeal. Conventional Pro Logic decoding lends itself perfectly to motion picture soundtracks."