Linear Tube Audio MZ2. I bought it used for a great price and got lucky to boot. It's one of the last ones built and the circuitry is closer to the MZ3. Just a beautiful sounding piece.
Bryston 3B Cubed. An upgrade to my Parasound A23+.
SVS PB2000 PRO Sub.
PD Creative LPS for my Node 2i.
Marchand Electronics Balanced HPF. Part of my experiment with low end control. No longer using it in favor of a another unit.
White Instruments Model 4856 Active Equalizer. This replaced the HPF. It has a HPF built in.
I also built new crossovers for my Vintage JBL 4311s.