Synergy is basically matching components that compliment each other.
Example : Amplifier matching
I have had two pais of 80dB speaker (ATC SCM10 and Keesonic Kolt). I have tried a variety of amplifier with them-
Bantam Gold (15wpc), T-Amp (8wpc), Decware Zen SET (2wpc), Denon PMA-2000AE (80wpc), Sony TA-F670ES (90wpc), Rega Brio3 (38wpc), Arcam AVR200 (85wpc) and Sony TA-F770ES (90wpc).
And the best with the Kolts was the Decware, T-Amp and 770ES. Now thats quite a large range of power outputs that seem to work really well, when in theory it should not. The Decware worked really well just from a 'hifi' view as it had the best soundstage, amazing mid-range and a very fast, punchy mid bass. We measured it and it was producing about 1% 2nd Harmonic distortion at ~0.6w output, and you know what, it sounded great!