Does the AV Receiver changes sound quality?

[ChrisColtCannon]

Obviously, i know new receivers can decode HD Lossless Audio Multichannel things like Dolby TrueHD & DTS HD Master Audio.

But does it change the Audio Quality itself. Im sure Lossless sound good, but will i even see a difference for normal Dolby Digital 5.1 Audio? (For upconverting DVDs for exemple)

I have an old Technics Audio Receiver bought in the Dawn of the DVD-era.
And old Front, Back-Left, Back-Right speakers bought from the same era.


Will the difference be obvious (excluding the lossless thing) ?

I have The Matrix Trilogy in Blu-Ray but it dosent sound that good, i mean its allright but im not really satisfied. But watching the review the audio had a 5/5 stars rating.