Passive Preamp for Atmaspheres?

I don't know the answer. I suspect that the Atmasphere's input impedance while not absolutely ideal is more than adequate for a passive. I don't know the sensitivity of the s-30, but I suspect at these low power levels it should be OK too. Of course, your source components and cables will have some bearing. In this regard the Arcam should OK. I'm not personaly familiar with most of the gear you have or are contemplating, but, from what I understand the tube pre's you are considering may sound very different than a passive. Sorry, I can't offer any real concrete advise. Good luck. BTW, Your system appears to have really good potential.

I ran my A-S M60's through a Melos SHA 1 line stage (single ended) and the sound was good. Ralph Karsten at A-S strongly recommends a balanced pre-amp design in order to acheive the best that his amps can put out. So, due to cost restraints, I opted for an Audio Experience Balanced line stage. The difference was truely remarkable. As a result of my own experience (as well as the designer's recommendations) I strongly urge you to explore true balanced pre-amp designs, you will be happy you did. Happy Listening,

Disclaimer, I work with Superphon preamps...that said, Superphon preamps by Stan Warren are available with or without gain, active super clean sounding preamp... might want to look in to these here on Audiogon Rev III model is the current and best version now being handmade made after extensive research and testing by Stan Warren. I would check the parameters the amp manufacturer sayd his amps want to see from the preamp to make sure ahead of time you have the correct match. Superphon.com
Best with the music...

The closest I can come to shedding light on your inquiry is to note that a friend of mine used to run M60s via the built-in volume control of his Wadia 861 into Merlins with good results IMHO. Almost all of his repertoire consisted of jazz and small ensemble music. I don't know how electronica or bass heavy music would fare but my impression is that it survive mostly intact. I personally run M60s partnered with an MP-1 and find it transparent enough that I don't have the urge to unplug it. Of course, an MP-1 is a major financial commitment relative to just about any passive. I myself am curious as to what others will share here.

I use the Scott Endler attenuators with my M60s, when I'm using a fixed output CD player.

If your run isn't too long, and your only source is the Arcam, you may well want to try these as well. Even if you decide to use additional sources, such as a tuner, I still think a passive preamp can be a good way to go. When I use the variable output tube section of my CDP, I don't use the attenuators at all.

You do gain a little by going into the Atmas via a balanced cable in terms of a lower noise floor. So, regardless of whether you go with an active or passive preamp, or direct, having XLR connectors on one end of the cable allows you to take advantage of that.

In my experience, I have not tried the AtmaSphere preamps (maybe I should?), but none of the other highly regarded units I tried ever came close to not having a preamp in the system. Worst of all is when a preamp imposes its signature so strongly that much of the OTL magic in the Atmas was hidden to a great degree.