midrange forwardness

Could any of you tell me how to get more midrange? My system (solid state) is a bit lean and laid back sounding. I would like to have a full sounding midrange and a sound that is somewhat tilted towards the lower midrange. Thank you.
System: MBL 1621 transport-Accuphase C-290V preamp-Gruensch CSE II se power amplifier-Soundlab A-1 (electrostatic) speakers.

Chris