Preamp

I am in need of a preamp or circuit....
I am coming out of a modded ART DIO running a Nakamichi amplifierthat powers some Vifa eqipped nearfields. The sound is incredible. Unfortunately I now have no sub output. The pass through of my sub is robbs the quality and I am without manual attenuation or headphone amplification. I need a solution which will allow me to keep my clarity and detail.
Thanks in advance