I use a PS Audio HCA-2, which is a digital switching amp. I got it used for a great price, and it sounds amazing paired with my VS VR-1s. I've only heard one system in someone's house with an amp over $3k, and this definitely doesn't slay that giant. However, for what I got it for, it might take on some of those amps costing $1000 more.
I was considering a DIY with the ZA Pulse, but once I started work, I no longer had that kind of time.