I havent heard the Audience 42 but a lot of people really enjoyed that line. Ive only owned speakers from Dynaudios Contour line. And based upon your current setup I dont think you would enjoy the Special 25... You need big amps to drive them and they are very revealing. (i.e. your sources will all need upgrading...)
If I were you, I would look at upgrading the speaker cables first. Try to buy a used pair of Harmonic Technologys Pro 11s. They mate very well the Dyns and will reveal everything the Rotel is out putting. From there I would start looking at upgrading the Rotel receiver. If it has preamp outputs, you can keep the receiver and use it as a preamp. Look into buying the best quality Solid State power amp you can afford. And then someday upgrade the preamp to something tubed... then go for the sources. Oh what fun!!!
Youll love the journey and enjoy the sound. Let me know if you get to hear the 25's... they do allot very well.
Tony