I use in my reference system both the Concert Fidelity preamp and battered powered DAC. Both are, as you know superlative. The amps are equally wonderful in their performance. Silky smooth, highly detailed-but never in your face, slightly warm in their overall tonality. I have heard a full Concert Fidelity system many times at Audio Archon, located here in the Chicago land area, driving different speakers to great sonic beauty.