The Spectral amp requires significant current for its input driver, something Spectral preamps provide while others *may* not. Spectral amps require MIT speaker cables since the wide bandwidth requires a low pass filter or Zobel network to prevent potential amplifier oscillation due to RF resulting from the Megahertz bandwidth. Spectral's approach is that the cable is part of the system, which makes sense when you think about it. I owned a Spectral DMC-20 preamp; incredible dynamics but a bit too brilliant. I also have a Rowland Model 2 amp and battery, which is very clear, a bit round and warm but with purity of timbre. Rowland M6/M8 also use input transformers, something I've found to be very beneficial and have added to other parts of my setup to break the ground noise from leakage current that's tied to the equipment chassis. TIs do this safely; lifting the safety ground on a plug is a dangerous way to float equipment. I'd say Rowland and Spectral are opposite approaches. Both are interesting. I'm considering adding a DMA150 myself for an alternative system. The difference is that you have to really go for a Spectral preamp/amp/speaker cable system to do it justice (why have a wide bandwidth amp if the input is rolled off? Defeats the purpose). Good luck.