Tubes and less sensitive speakers

Regarding proper subwoofer integration, I would caution that while this is a valid approach, in my experience, it can also be quite challenging due to the true dipole dispersion of Maggies.

@blisshifi IME the way to do subwoofer integration is to make sure the sub does not reproduce anything above 80Hz (otherwise it can draw attention to itself) and if there is only one sub, aim at a wall at an angle so the bass wave bounces off of it like a cue ball. This will help reduce peaks and valleys of bass in the room caused by standing waves.

Magnepans are typically very inefficient and require high current amps to get the best out of them. 

@jeffbij Just so you know, this statement is false. 

To understand why the first thing you need to know is how current plays out in a speaker like this, which is a fairly resistive four Ohms without odd phase angles.

To make 200 Watts into that speaker you need an amp that can make just a tiny bit over 7 Amps. As you probably know, in the scheme of solid state amps that's not a lot of current.

A 'high current' amp is probably called that because it can double power into 4 Ohms from 8 and maybe again from 4 Ohms down to 2 Ohms. But the Maggies really don't require an amp that can drive 2 Ohms with double the power. They only require that the amp make power into 4 Ohms and can do it in such a way that very minor variations in impedance don't result in variations in output.

Many so-called 'high current' amps advertise a current rating that doesn't square with the power ratings they claim; IOW the 'current' stated is often far more than the amp could ever produce. That is because that rating is the amount of current that would flow for 10milliseconds if the power supply were shorted out. Its not anything to do with the power the amp can make.

Since the speakers don't have a box, they don't have the same sort of resonance that requires a low output impedance to control them, even in the bass. They just need the amp to be able to make the power.

It is true Maggies don't seem to be very efficient. But since they behave as a line source, you really have to add about 6dB to their measurement to understand what is going on. If you've been around a set of Maggies, you may have noticed that they sound just as loud ten feet away as they do when you are only a foot away. That is because at a distance, more of the output of the speaker is reaching your ears while when close up it does not. The same is true of a microphone placed 1 meter from them.

So this means the speaker really is more sensitive than the rating suggests. The model 2.7i for example is similar to an 8 Ohm box speaker of 89dB or a 4 Ohm speaker that is 92dB.

I thought I heard Atmasphere amps can work well with Maggies but could be wrong.  Worth checking or maybe @atmasphere can chime in. 

@soix We have a number of customers using our OTLs with Maggies. The smaller amps like the M-60 tend to be used with the smaller Maggies in tandem with a set of ZEROs. The bigger Maggies like the 3.7 might have MA-1s. Willard Diller of Magnaplanar used to make a point of telling me the best he ever heard the MG20s was with a set of our MA-2s.

At any rate, if you want the best out of the tube amp, whatever it is, it makes quite a difference to keep the speaker cables as short as possible. To this end I've seen 8 inches of really heavy cable (8 gauge) make an enormous difference in how the amp made bass impact as opposed to 6 feet of a regular cable! But to do that you need monoblocks so you can put the amp right behind the speaker so its speaker terminals are as close to the speakers as possible.