Pros: Excellent Sound...no noise in quiet parts of songs, no cracks of music,
Cons: Wish had more extension out of box, but thats what opamps are for
Wish I had something to compare to. Had an audigy 2 for years and thought extension was better in treble. But Audigy 2 does not have a headphone amp and cannot push the HD650 properly. Not even sure it can push the AKG Q701. The HD600 with the audigy 2 are fantastic since HD600 does not need a headphone amp. I am a pretend to be audiophile since I have a limited budget.
Althought I do have tons of headphones: I ripped all music to wav file using EAC. I feel at times I need a headphone tube amp to improve sound. When I tested my STX against a Sony 400 disc CDplayer to receiver, both sounded exactly the same. So I stuck with the STX and ripped the CD collection to WAV.