I'm more on line with 20% too. This probably doesn't include the QX4 and QB8. Only you can judge and try to it with some sort of blind comparison. The changes are typically not shocking but should be closer to natural if that makes sense.
How to allocate my cable dollars.
I have a Classe processor (SSP-800), McIntosh amps (501), and B&W speakers (802). I've been talking to my hi-end audio store about upgrading cables. My current cables are rather inexpensive generic cables. How do I allocate my dollars between, interconnects, power cables, speaker wire, and HDMI cables? On which cables should I spend the most and where the least? Where does higher dollars spent result in the most bang for the buck?