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I've been the proud owner of an eclipse 5506 for a number of years now (for the last 2 or so it's sat in a closet but that's another story) and I recently aquired a like new 55090 DVD model. My primary question is what are the differences (primarily in regards to sound quality). Both have copper chassis, with 8V pre outs, Both have commander capability and dsp capability (although I'm not sure if they use the same dsp - anyone know?), I know the 55090 has a fiber optic - toslink connection - does anyone know what it's used for?

One or the other will be going into my millenia. with 3 eclipse amps, boston pro 4" fronts, nakamichi 6x9 rears and an Alpine Type-R 10" sub.

Thanks in advance for your help.