SET amplifier (for AvantGarde Duo's-original) recommendations

Hello all,
I inherited the above speaker and I have been really enjoying them.  I also have a pair of Thiel 3.7s- paired with pass labs xa60.5's (and it works!) which I also love albeit they are very different animals from the DUO's as you can imagine.

Right now I am focusing on the Duo's and have used them both with Pass Labs and a Mastersound Compact 845- both are great but there is something about the DUO's driven by this 845 SET that is magical.   The problem is that the 845 was dropped and developed a hum.  A technician went through it and managed to reduce the hum but it is still there and it bugs me- I am not sure if one of the transformers itself may have been damaged and that isn't really repairable at reasonable cost, though I will speak to Mastersound to hear their thoughts. I should add that the amp used to be dead quiet and generally Masetrsound makes superb amps- and are renown for their transformers.

So I am now starting to think about alternatives solutions- I would like to either stick to a SET of comparable quality (that is known to be relatively quiet with efficient speakers)- maybe a 300b type just for a change, or even an OTL.

There's a lot of stuff out there at the moment, take the Line Magnetics that are floating around (but would they compare to Mastersound in terms of build quality etc?) and I was hoping to get some insights on what you think would work well.  I have read a lot of reviews and while helpful at times I feel they are almost always positive and a little too generic  when comparing similar products.  I'd like to stick to a $5k or so budget (therefore I would look for something used).


Have you looked at Whammerdyne? I have their DGA-1 (2a3s) driving a pair of Spatial X5s. Obviously the Spatials (open baffle, 97 dB) are very different from the AvantGardes, but wow that Whammer is special ... and absolutely quiet ... and in your price range.

@pgastone I’m a huge fan of SET amps and Avantgarde. What a wonderful direction you’re going in. While 300B are amongst my favorite tube type, I agree with others that speed and resolution are equally important to the bloom that you seek.

In this type of application, my favorite amps are custom built by an engineer out of Brooklyn named Oliver Sayes. I have a Korneff 45 clone from him that uses Hashimoto transformers and upgraded capacitors with Russian PIO, Audience Auricap XO and Mundorf. The amp uses a tube compliment of a pair of EML 45 Mesh, a single 6SN7 where I employed a Shuguang Black Treasure (the only place I’ve ever permanently lived with this tube), and a Philips 5R4GYS rectifier. All in all this build and configuration with tubes can probably be had for less that $3500, with tubes costing almost half that. 

While I didn’t own Avantgarde, I did use this amp with Oris 200 horns using AER drivers and they were lovely. I unfortunately no longer have the horns as we had to repurpose the room for that system for something else, but I still do own the amplifier and now use it as a headphone amp to drive my Audeze LCD-4, and it is killer!

I have AG Trios and have demoed many amplifiers on these high efficiency speakers.  The good news is you do not have to spend a lot of money on amplification to get really excellent sound.

I have two integrated amplifiers that I alternate with as they have rather different sonic attributes. My favorite is the Elekit  TU-8600 with the Lundahl transformers.  Herb Reichert has reviewed these and are in his reference system.  They sell for around $2200. My second amplifier is a Sophia MC-300 A which has a more full sound and bigger image. This amplifier is a little more expensive at $4000.

On the downside, the efficiency of these speakers makes mitigating hum a top priority so be sure to demo before you buy.

Once you become accustomed to the dynamics, both micro and macro, of high efficiency horns you will find it hard to go back to conventional drivers.

I have been running Duo’s since 2006 with Atma-Sphere S30 Mk3 OTL stereo amp. The amp is dead quiet and produces a wonderful sound. At ear-splitting levels it wasn’t even showing 1W on the meter.


I’ve recently changed to AGD Audions and these are also a terrific match with the Avantgardes. You could also have a look at Atma-Sphere Class D monoblocks which are getting great feedback.


I agree with @lubachi that you don’t necessarily need to spend a lot on an amp for these speakers as they are so easy to drive with their high impedance/efficiency.

Oh boy! there is a wealth of information here- I cant thank you enough for all the suggestions.  There's a lot to ponder.  One thing that surprised me is that in some cases we are talking about very low wattage amps and I was always a little concerned that while the speakers are very sensitive as some 100db, the nominal 8Ohms impedance, albeit good, would require a little more power  (that said, the Mastersound Compact 845 is overkill in the other direction).  It sounds like I should reconsider my assumption.

I have been intrigued by Atma's- at the risk forcing you into worn out cliche's how does the sound these compare to a SET or Audion's.  Good to know they are quiet which brings me to

Hum is one indeed one of my biggest concerns.  The problem is that auditioning is not always easy.  Someone had indeed suggested Sophia electric to me (the 300b mono's) and it sounds like noise is unlikely to be an issue assuming these are as quiet as the MC300 you mention.  I'll look into the Elekit as well- it is interesting you prefer this to the Sophia.
As for the addictive nature of the immediacy of horns it is indeed very hard to go back (though I am still very impressed by the Thiels when I get a chance to hook them up).

I have heard about Oliver Sayes and seen some of his amps pop up for sale.  And since I live in Westchester and work in NYC this sound very intriguing. How does one get in touch with him?

I had not heard of these.  I'll take a look

I have looked at these, but as I mentioned above I simply thought that the DUO's needed a few more watts,  I have to say the Triode Labs look ver impressive in terms of fit and finish.

@antigrunge2  and @acresverde 

Yes, Atma sphere keeps coming up- and I have never tried OTL so I would love to audition (and it would like not to have to deal with 75lbs beast- thus the acceidnt with the Mastersound).

Those Decware amps look amazing- not familiar with them and it sounds like I should be.  So really?  I can get away with 2 watts?
Just by everything that has been written so far seems like I was dead wrong about the required wattage- if this is indeed the case this opens a whole new other world of possibilities.

I would indeed be interested. Please tell me more- email is pgastone@

Another one I was not aware of!  And I thought I was generally well versed in the possible alternatives.

A lot of good press for the LM's- my only concern is that a couple of times I have heard they aren't always super quiet.

Yes, I saw that Audion- thanks for the heads-up.  My budget is $5k but I wouldn't mind going a tad lower if possible.  YTha said, the unit in question has a great reputation- a similar version is listed on the Music Room website.

Wavelength make great products but they are  out of my price range.

So it sounds like
a. I should castt a wider net to include lower powered SETs
b. 300b might not necessarily be the only choice.

There is a seller that has a Mastersound 300b for a little over $4k but then of course there is the shipping and a tube upgrade (they are all stock- they are ok but there is scope to upgrade).  And with everything I have read here I am staring to lean towards exploring some of these great suggestions.