Moresampler and the fresamp engines tend to boost the strength of voicebanks, moresampler especially if setting the Mt flag to a raised setting. Hifisampler, although it tends to make voicebanks a bit softer, sounds clearer and has its own version of Mt, Ht. You can also try getting some of her other voicebanks and seeing if any of them are more powerful. I don't know Miko all that well, and so don't know exactly what her voicebanks are.