I recently built a unit for a friend. This picture shows its internal structure. My friend uses it to driver his JM Lab floorstanding speaker. The sound is so transparent and fast!!! He likes it a lot and brings it to show his friends.
The copper bars and entire case are heatsink. Power supply: 300 VA transformer, Sanken ultra-fast recovery diodes, 22,000 uF x 2. Small transformer is for the speaker protector.