Spectral products are outstanding, and there does seem to be a synergy between the amp and preamp. I have the DMA 50 (purchased for less than $1000) and the DMC 15. Between the DMC 15 and 20, go with the 15 if it's in the budget. DMC 15 was smoother, and at the same time more informative, than the 20, which is a fine preamp when considered on it's own. Never compared to the 30, since the DMC15 new was less than a used 30. I've heard others say they're even, the advantage of the 30 being remote control which is absent on the 15. I'm driving thiel 1.6 with the DMA 50, and it's reputed to be a warm amp, and it does sound great with the thiels. Since I've had the spectral amp/preamp, I've never thought about upgrading, I'm happy where I am. Before, I was always looking to upgrade my amps. There's another spectral that's supposed to be warm like the DMA 50, I want to say the 180, but don't quote me on that one! It's great equipment, and from time to time, there are some fantastic used deals on Audiogon.