any decent pair of tube mono block amps would work fine in all probability.Solid state tends to make the Martin Logans sound cold.
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The ML's are not all that inefficient, they are rated 89dB/watt at 1M, which is about average these days. But they DO have a low impedence dip of 1.5 ohms. This drives most amplifiers just wild. Tubes suffer most, as their transformered output is only designed for a level-impedence load, they have taps for 8 ohms, 4 ohms, etc. At other impedences, and into reactive or capacitive loads, (and the ML's certainly qualify for THAT), all tube amplifiers and some solid state amplifiers distort and/or modify their frequency response output. One's impression of "cold" or "warm" is actually caused by the modificacion of the frequency response plus added harmonic distortion, lots of it in the case of tubes, like 5% or 10%, as the amp tries to drive the difficult load that the ML's present. The SOLUTION to this situation is to purchase an amplifier that has large current and voltage capability at low impedences, and that has enough power to drive the ML's to a reasonable level at the same time. To play the ML's at 103dB, one needs 256 watts of amplification (it's a simple mathematical calculation). Then it's a question of selecting an amplifier that provides this power into the ML SL3's 4 ohm nominal impedence AND can drive a 1 ohm load to the approximately 800 watts needed to provide a flat-bandwidth output. There are many good solutions, some for even under $1000. Not to mention brands here, feel free to email for some suggestions.
I have the Martin Logan Aerius, the smaller version of the SL3's and use a pair of Meridian 557's (400 watts into 4 ohms and high current delivery) which sound wonderful, you need power of this order to make them sound right, plus bi-amping as I have done with one amp for the panels and one for the bass makes a HUGE difference to every aspect of the sound quality.
If you're the type of listener that is obsessed with "breaking-glass" cymbals and "thunderclap" bass, you're gonna need solid state with plenty of watts which cost plenty to do right. If, like me, you prefer to get directly to the heart of the music ...put on an album and enter the world of live, in-room entertainment presented for your exclusive attendance, you've just got to try single-ended triode tubes. Admittedly, the majority of designs are low (less than 10watts) in true Class A / Zero Feedback (The ONLY way!!!). There are however a few designs which take advantage of the larger 211 and 805 power tubes, and can double that power delivery! Don't be discouraged by the maths! These amps will drive loudspeakers that they shouldn't. My 8 watt Cary's drive anything 88db sensitvity upwards. And don't believe that the bass is soft and furry. What's there is timbrally correct and tuneful. But the heart of the message is in the amazingly natural and wholistic sound that can be achieved. With a superb investment like the SL3's, you owe it to yourself to find a good dealer who is not only honest enough to admit that no, he hasn't actually heard it for himself - but will also go to some trouble to set it up for you. The Cary equipment gets my highest praise by the way. Good luck!
The amp I currently use with my Martin Logan reQuests is an Aragon 4004MkII (200W/C)-- not bad at a fairly resonable price point used (approx.$800-$1,000). However, I just auditioned an Audio Research VT100MkII. It not only handled my reQuests with aplomb, but provided the sound I had always wanted but had not found until the A/R. Other amps auditioned were Bryston 7B-ST monoblocks and QuickSilver monoblocks. Neither came close to the VT100.
Olivier, you made a good choice there. I have the SL3's myself and found the biggest difference was made by the use of Alpha Core Goertz AG1 speaker cables in a biwire configuration. As someone else here mentioned, these speakers have a dip to about 1.5 ohms, which can strain almost any amp. The Alpha Cores somehow relieve (dunno how, I'm not an engineer) the strain and let the music flow. Find a dealer who has them or buy a pair and re-listen to your amp choices. I believe there are a couple pairs for sale here and at some other sites. You can also go to www.alphacore.com/goertz.htm and check them out. By the way, I am now using the Muse 160 and am very happy with it.
I am biased as a principal in the company, but Clayton Audio's S40 and M70 monos work extremely well with the SL3s. You need current and that's what you get -- pure class A (most so-called class A amps don't do full A till their rated output. Ours do.) We have sold several amps to ML owners who have tried many, many amps without success. Our amps were developed using MLs as a principal reference. Audio Adventure used our S40 (40 watter) as their reference amp with the SL3s. Audiophile producer John Marks has publicly praised our amps and he heard them with SL3s -- a speaker he normally thought was cold and dry. I own SL3s myself and drive them with M70s but the S40 works fine for normal listening. Look up our reviews (TAS, Positive Feedback, Soundstage, etc.). Or email me and I'll be happy to give more info.
ML's reputation for being hard to drive is way overblown. I sometimes wonder if everyone giving opinions has even heard these speakers. First, SL3's are no big deal to drive -- they aren't even real electrostatics -- why do you think that ML compromised sound and went to hybrids in the first place? The more "advice" I see regarding ML's,(not on this thread since most people here have SL3's), the more convinced I am that most people have never owned and lived with -- maybe never even heard -- these speakers. They are not so hard to drive. No more fussy about set up than any other good speaker. Period. By the way, I DO own ML's. CLSII's (no Zzzzzzzz and still not not a problem). And, no stinking woofer to spoil things. Any high quality ss amp is good for pure electrostatics, but tubes are even better. Sweating amps for SL3's is mental masturbation. Look at the variety of amps mentioned here -- and great sound, to boot. Again, these speakers are no BFD to drive. Your decision regarding an amp is not much different than if you had any other speaker. Really. If you were running pure electrostatics, this would be another matter. Don't get sucked into the "hype". Spend your $$$ elsewhere in your system unless your current amp is really bad -- you didn't mention what you're using -- this will most likely make your ears and soul happier.
I just bought a pair of SL3's and I was going to try the Sunfire Cinema Grand(biwiring the 3rd and 4th channel for stereo use until I can afford the center and surround channels. I noticed no one mentioned Sunfire equipment, Any reason? Also will the Sinema Grand be able to handle the dip to 1.5 ohms? The amp is only rated at 2 ohms, thanks for helpful comments.