Monoblocks or upgrade to larger amp?

I have a Plinius SA 100 Mk.III amp with a Audio Research REF 1 pre-amp, Meridian 508.28 CDP, Dynaudio Contour 3.3 speakers using NBS Monitor I ic's and Monitor III speaker cables. I love the sound on this system. However, I'm considering upgrading the amp to either the Plinius SA 250 Mk IV, or get another SA 100 MK.III and use both amps as monoblocks. What do you all think would be the better way (sonically) to go? And why? From what I understand using monoblocks provides a "cleaner" stereo separation and better soundstage. However, will upgrading to a more powerful amp provide greater detail?