Upgrade speaker cables OR amp for Dynaudio C4's?

I have approx. $1500 to play with. Not sure if I will get more bang for my buck by upgrading my amp (Plinius SA-102, class A 125 WPC) , or my speaker cables (Harmonic Technology Pro 9's)

The rest of my system consists of:
- Speakers: Dynaudio C4's
- Preamp: Aesthetix Calypso with NOS tubes
- Source: Audio Aero Capitol MK 1 CDP

Amps being considered:
- Pass X250.5
- Moscode 401
- Parasound JC-1's

Speaker cables being considered:
- Kimber KS-3033
- Stealth Hybrid MLT

I'm happy with my Plinius amp... I just wonder if I'm missing something by not feeding my Dyn's with more power. I listen at moderate levels... mostly classical, jazz, female vocals, acoustic rock.