hgeifman- I've had the new Atma-sphere class D monos in my system for exactly 3 weeks today not using a pre-amp and they sound fantastic. I researched whether or not they could be driven by my Cary DMS-600 before I took the plunge. They are replacing my tube amp. I've not used a pre-amp in 11 years so couldn't tell you whether a pre-amp would improve. The tube amp I ran was a Music Reference RM10 MkII which was ideal for running direct or with a passive pre. The monos sounded good out of the box but after 3 days came alive. I'd really like to try an Atma MP-3 with them but it would be a rather expensive experiment. I was told by Cary that the DMS-600 is truly balanced so I'm not sure I would gain anything. My system is posted here. Contentiousness abounds, LOL! Now back to listening to music cheers.