What kind of power needed for Martin Logans?

It depends on which Martin Logans. In general, they have the ability to go to very low impedances (panels). This coupled with the demand of the dynamic bass driver can create a staggering load which is difficult for many amps. Some of the newer models (ReQuest, SL-3) are a bit easier to drive as they have increased the impedence. I have bi-amped a pair of Monoliths, which gets away from the problem entirely, but prior to bi-amping I would look into high power hi current amplification--generally class A. The bryston is not class A running and will not be great sounding with the panels. Amps that I generally like are older Classe (model ten) and Levinson (twenty series--I think the 27 had the highest power in the 20 series). Some people feel tubes really work well with the MLs, but I don't have much experience there, so will let others comment on which tube amps might work well. My guess is for the power and demands you will need for both musically and theatrically (HT) satisfying experience you will have a difficult time beating a solid state amp.

I have SL3' that are powered by a BAT VK500, which is 475 watts at the speakers nominal 4 ohm impedance....these speakers need at least 200 watts to sound their best and don't do well if underpowered. The transients the panel can produce need as much power as you can afford.
Regards,

I very much agree that a high current aamp is required. I currently have SL3s with an Audio Refinement Multi 3 amp, it works great. I've heard MLs with all sorts of amps - I used to have Aerius with an ARC D-130 which also worked well. I've even heard the Prodigy driven by an ARC VT100 MkII - it was surprisingly powerful enough to drive the big Logans. You would be safe with any of the amps listed above, the only one I haven't heard is the older Mark Levinson.

Look for an amp that uses very high rail voltages with a BIG "high current" transformer. This type of amp tends to work best with E-stat's. The first ones that come to mind are Perreaux's and the Innersound amps. The Sunfire amps, primarily the Signature, will also work quite well with these. They may not have the "slam" that the Perreaux offers though. Audiogon member "Hotrod" works at Martin Logan and seems to LOVE the Sunfire / ML combo that he has.

For the record, there is a BIG Perreaux amp listed for $850, which is a STEAL !!!! 500+ wpc @ 8 ohms, built like a TANK ( weighs 105 lbs ) and will drive ANYTHING with the best bass you've ever heard. I am not selling or associated with the guy that has it listed. Sean
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Minimum of 150 watts into 8 ohms. Since these speakers are 4 ohm's the power rating will be almost doubled. I use a 200 watt into my ML SL3's. This gives me almost 400 watts into 4 ohm. I get plenty of power at no where near the half way mark on my pre-amp!! Steve