Mac-Mini to Home Stereo Sounds Harsh

Hi all-

I am making the move to lossless music on network storage device, pull it off with Mac-Mini and then run it into pre-amp. I have been reading the threads on music storage formats and for this discussion I have used raw PCM packaged as .aiff, .wav, and also Apple lossless (.m4a) and all appear to have the same issue. They sound somewhat harsh and the soundstage is not the same when A/B with my Rotel CD/DVD player.

My Rotel pre-amp has 2-digital optical iinputs. One for my Mac-Mini and one for my flat panel over-the-air input. Neither of these sources have optional connections so must use the digital optical.

The Rotel CD/DVD player can be connected by digital coax or digital optical (tos) but since no more digtal optical on my preamp, it is connedted to the Rotel pre-amp with digital coax.

Both cables are Tributaries cables.

Obvious difference is Toslink vs coax. Again, this is done b/c of limited ports on Rotel pre-amp.

I am want to convert my entire collection to some type of perfect source (like many others). I need to pick a format (another discussion within itself) and will most likely use .aiff or .wav or the Apple lossless .m4a BUT all exhibit the same problemof thin soundstage, edgey/harsh musick so I am kinda bummed.

Any ideas? Is digit coax really better than tos? I didn't think so. No sharp bends in my fiber cable. I am using Tributaries cables. Perhaps the interfaces on the components?

I ripped the soucre with iTunes using the Advanced tab to choose the various formats.

My goal: Perfect source (hehe) on Gigabit eithernet Network drive. Mac-Mini is hard wired to gigabit ethernet. Pipe the music from network into pre=amp via Mac-mini and have all my music at my fingertips with no loss of quality.

I do plan to upgrade my Rotel Pre-Amp/Amp later but for now want to get my source nailed down and choose the proper connections.

Advvice, help, opinions? I would REALLY appreciate your help.

I did see something about connecting the Mac-Mini to pre-amp via some type of USB converter but do not understand this method and not sure if it would improve the scenario or introduce more confusing variables. Saw a post about a certain converter (HagUSB or something like that).

Think that sums it up, again...appreciate your help and value your thoughts.