I have demoed both with a MSB Platinum Signature DAC IV with Signature USB interface. I liked PM 1.82. It sounded great. It had a wide deep soundstage and was very warm. Buy in my system and to my ears Amarra 2.3 sounded better. It had better low end extension and the vocals and instruments sounded more fleshed out and realistic. Also Amarra seemed to provide a level of dimensionality that was lacking in Pure Music.
YMMV,
Johnny
YMMV,
Johnny