Amplifier for Avantgarde Duos

I'm looking for an amplifier for my Avantgarde Duos. I'm currently using an Art Audio Carissa with an ASL Flora for the pre. With this combination I still get a shrill presentation on some recordings. My pre has a nice rounded top end so I feel comfortable with it. Does anyone have any suggestions for the amp. Again I prefer something that softens the shrillness. Some amps have a lean top end. The Carissa is almost there.