Sennheiser pc 130 (USB)
Logitech G35 (USB)
Roccat Cave (5.1 Surround, connected to Creative Xfi Gamer, and USB for power)
Not all three at the same time.
Sennheiser in normal mode, running TS from a second computer. Game sound via 5.1 speaker set.
G35 and Roccat when on 'silent mode', TS and Game sound through the headset.
All three have their own volume controle, Sennheiser and Roccat have that in a controller in the lead, Logitech has a control on the set itself.