Zero Feedback: Atmasphere vs. BAT

Do Atmasphere and BAT have similar sound because they both use low or zero feedback tube designs?

I am considering these amps for my 8 ohm 89db Spendor S8e's.

I am looking for smoothness, Transparency and sound on the warm side. I am leaning toward a BAT VK75, it can be upgraded and it runs AB instead of the hot class A. You can also upgrade to VK 150. From what I can gather the 140 watt MA1 is superior in the area of dynamics, that would be the main reason to go Atmasphere to the best of my knowledge as OTL is super fast and more of a rock out style.

I am looking for used gear that can be supported over the long term by a good company.
I own the Audiokinesis Jazz Modules and have heard them with the S-30 amp. I believe Duke even voiced them with the S-30. Atma-sphere amps have a high output impedance (the S-60 is 4.1 ohms). I think one of the reasons that Atma-sphere and Audiokinesis are a good match is due to the impedance (no lower than 8 ohms and closer to 12 ohms) and smooth frequency response of the speakers. I currently use mine with VAC Auricle Musicblocs.

Personally, I've never liked tubes and Spendors and I've owned a few pairs of the Classic Series (the Jazz Modules replaced 1/2e's). If you are considering selling the Spendors you could do a lot worse than an Atmas-sphere Audiokinesis combo.
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.
Well, I can confirm that the combination of the Atma-Sphere S-30 and the Audiokinesis Planetarium Beta is superb. I assume this would extend to the Jazz Modules as well. I live near Houston, which certainly gives New Orleans a serious run for its money with respect to most intolerable summers. The S-30 puts out heat, sure, but is really not a problem. It is as neutral as they come. Look elsewhere if you want warmth, at least the artificial kind.

By the way, guys, the model numbers are "S-30" and "M-60".

With all due respect, IMHO, you are taking a wrong approach. Speakers are a much more difficult DIY project than building amps. If you are on a budget and are interested in DIY, I would suggest you buy a pair of high efficient speaker used, something with at least 95db+ sensitivity; and build an amp to match it. If soldering isn't your cup of tea, than forget about DIY, save some more money and buy a used amp.

I used to be a DIYer myself may years ago and had built many amps and speakers. Most of the amps turned out great but none of the speakers were good.

Don't build speakers if you want to save money. You will end up spending more.
Your statement about BAT being "very lean" does not support my personal experience with various BAT pieces- BAT VK-75SE,
Not at any point of time, paired with different speakers, did any BAT sound anywhere close to being lean.
It sounds full- bodied, very dynamic and textured.