We had the volume level pretty closely matched. The differences, in this particular test, could be best described as "fatiguing". The all-purpose Dolby Digital/DTS/etc. decoder just didn't sound quite as "good" as the single-purpose two-channel DAC.

Personally, I'd never spend that kind of cash, but there are real, noticable differences between different components. Back when I bought my Arcam AVR300 receiver for driving my 5-channel setup, I compared it against a cheaper NAD receiver driving the center and rear channels with an off-board NAD (or was it Rotel?) two-channel amp driving the main speakers. The sound with the all-in-one Arcam was just better, particularly the bass. Was that due to the decoding software? The quality of the DACs? Power supplies? I have no idea, but there was a subtle difference, so I went with the cheaper / better solution.