The ecp audio amps (l2 or dsha-1) could be something to look into. John loves his dsha-1 and felt that the Apex Arete/Volcano was too sterile I believe.
http://www.ecpaudio.com/
Just finished installing 8GB RAM in my 2009 Mac Mini. Boy, the case is a pain to get off (well, at least the first time... next time I won't be so worried about breaking it).