If you live anywhere near a SongTower owner, you might want to audition the SongTower with your amp, if possible, but you won't be able to accurately assess their performance in your room. Notwithstanding, the SongTower, although not their ideal placement, perform well even when placed more closely to the front wall than desired. The SongTower will pair well with a tube amp of sufficient power and with the ability to drive a 4 ohm load, and the Cronus Magnum is capable of ninety watts and has 4 ohm taps, I believe. I heard the SongTower being driven with a 30 watt AVA UltraValve tube amp, and the UltraValve had more than enough power.
If you don't like your current speakers, replacing them is more than justified, IMO, and the sooner the better.
BTW, if you like Led Zeppelin, The Rain Song is great on the SongTower with good amplification. The track shows off the SongTowers' capabilities.
Good luck.