For "smoothness and transparency and warmth" it sounds like you are looking for a Cary, CJ or other el34 based amp; or perhaps a 300b amp.
Atma, IMHO runs pretty neutral. BAT runs very lean - a bit like Audio Research. So, no, BAT and Atma do not sound similar. IMHO, the Atma and Audiokinesis combo will be very, very musical and better many systems costing much more. The big Atma will heat up a room, but with a properly matched speaker, you will be fine with the m30 or m60.
Atma, IMHO runs pretty neutral. BAT runs very lean - a bit like Audio Research. So, no, BAT and Atma do not sound similar. IMHO, the Atma and Audiokinesis combo will be very, very musical and better many systems costing much more. The big Atma will heat up a room, but with a properly matched speaker, you will be fine with the m30 or m60.