as an ex-user of QC24, my experience is that it's quite good preamp for beginner level but its noise is quite obvious... you can hear the "si......" sound clearly even you turn down the volume.
moreover, the sound image quite large and bass control not very good.
it's esp good for vocal and instruments. but for classic, orchestra, pop and rock, you should look for other choices.
CAS (Win 7 64 bit / Audiolense / JRiver)
NAD M51
MC2 MC1250
Harbeth Monitor 40
Atlas Opus Coaxial, Supra Sword Cables