Love Bent-TAP, but not with Atma-sphere, the amp is not sensitive enough for a passive IMHO. What does work really well is a passive with the Music Reference RM10MKII ($1950 new, to $1,000 used). I had CAT JL2, Ars Sonum, Quicksilver, Music Reference RM9 & 10, and Pass XA30.5 and Aleph J with the MXe. To my ears, nothing beats the Atma-sphere M60s with the Atma-pre, but for a lot less money the RM10MKII is one hell of a great amp and it drives the Merlins beautifully with its 35 watts. If cash is no problem, Atma-sphere M60s with the MP3 is a world class combo with the Merlins (some prefer the Joule, but I think that is a matter of preference, and quite a bit more expensive than the Atma-sphere combo - though I do use a Joule LA150MKI Signature with my MR RM9s.