New Generation Class D - AGD Audion Mkiii upgrade

I have always had a preference for horn-loaded loudspeakers which, whilst typically easy to drive, can be quite revealing (good/bad) of any changes in the system. I am running Avantgarde Duo’s and have until now always preferred valve amplifiers for their mid-range and lack of fatigue.

I have heard a number of Class D amplifiers and one or two have sounded pretty good but a bit lean compared to valves. Tha changed when I purchased a pair of AGD Audion Mkii amplifiers. The Audions have an almost valve-like mid-range but with a wonderfully transparent top end and great sound-staging. It’s always been difficult to get really convincing bass with my Avantgarde’s because if you increase the bass level the low frequencies can sound detached from the glorious mids/highs. This changed with the Audions as the bass is faster, more dynamic and just overall more satisfying.

These compact amplifiers have what appears to be a valve for each amplifier. This ‘valve’ glows red and I rather like the effect. I did think this was a bit of a gimmick at first but it contains a Gallium Nitride MOSFET power stage. However, this ‘GAN-Tube’ means that if an improvement is developed you can just swap the tubes for the new version. That is exactly what I have done as AGD have launched a Mkiii ‘GAN-Tube.

I was extremely happy with my Mkii Audions and wasn’t sure what to expect with the Mkiii tubes. But as audiophiles it’s difficult to resist an upgrade. The new tubes were fitted in under 5 minutes. I’ve found most components need time to warm-up and ‘burn-in’ so wasn’t expecting too much initially. However, it immediately became apparent that, even at very low volume, there was more detail. I pumped up the volume and was astounded by the wider soundstage which extended beyond the speakers and allowed you to pick out instruments and vocals even clearer. This is something that I’ve found difficult to achieve with Avantgarde’s and I didn’t have with my previous OTL amp. Dynamics are a strength with horns and the Audions really produce a ‘live’ sound, quite startling at times. I’m not great at describing all the audiophile things but would just say that these amps make the system sound so enjoyable and exciting to listen to. They are the best by far that I’ve had in my system.

I know some people will have a hesitation over Class D amps (like I did) but I really think this next generation amps like the AGD Audions will become more and more popular once people get the chance to hear them.



Was using my AGD Audion MKIIs.

Actually, I now have ARC Ref 80S. Very similar to George’s Ref 160S.

And between the AGDs and the ARC I thoroughly enjoyed Ralph’s Class Ds.

The AGDs are beautiful sounding and very musical. However, Ralph’s easily surpassed them in musicality and, especially, in bass. They are much more substantial in many major ways.

At 3 times the price, the Ref 80S takes things to a new level. Contrary to Ralph’s position that the amps are now on “life support”, the tube magic of the Ref 80S makes it stand out in quite a spectacular way. Mostly, the ARC brings “life” without any need for “support”. A good example of “you get what you pay for”.

when you take it to the next level vs say a very good class A amplifier , or very good class AB amps of our well known Danish companies , then myself and many others are waiting for that , look at Merrill their insane pricing ,and IMO wasted $$ on these fancy cases , a respectable look and we’ll damped chassis is more important put the $$ inside where it counts, I highly recommend using a top Furutech IEC their $75 retail being copper and gold remove Thst bottleneck judt coming in , maybe upgrading some of the filtering caps ,or putting a decent .1 poly cap on electrolytics , or Bellison  regulators which are the best , man6 ways to make this a SE type quality as well as other higher quality parts look at Silmic or other smoothing  caps .having spent over 20 years just in experimenting with the tonal balances of each caps and Electrolytics by far the worst in noise and filtering with poly caps , output caps , look at VH audio Odam caps ,even wire !Neotech Teflon 6-9s pure Copper  wire makes a difference , or Cardas Litz  wire.

@audioman58 As you can imagine we've auditioned quite a lot over the last 45 years and we've heard them make quite a difference. But that was in tube amps with little or no feedback; when you are able to run very high amounts of feedback the circuit is able to reject these very same effects; in essence they don't win you the same thing that the did if the amp were zero feedback. Even though I knew that, it was still eye opening to actually see/hear it first hand.

@mglik One does have to be careful about the Veblen Effect. As I mentioned earlier though, the reason tube power amps are on borrowed time has to do with how class D is spreading in the musical amplifier (guitar and bass) world. Since you know about a prototype amp we sent to Ron Carter, you have a better idea than most how that works. Guitar and bass amplifiers are the bread and butter of vacuum tube producers; so its not hard to imagine where this is going in the next 10 years.


What’s you opinion of them say take a 6SN7 vacuum tube and use as a hybrid  ?

I see rogue doing this in a Less complex way. , I have been into modding Loudspeakers mostly myself ,but keep an open mind on the latest Class D modules 

and how to take advantage of this ,servos,and Switching is getting better and GAN transistors , how to make a better wheel ?   
how or why can Merrill try to justify over $20 k+ for their amps ,they are very good 

but  newer technologies are progressing think about how you too can make it better 

remove $$ constraints what would you add.  Look at T+A  their 200 dac for example is excellent and beats the competition at less then 1/2 it’s cost.

switch mode power supplies can in fact be better then Linear power supplies ,

they have clearly proved that .  That’s why I am waiting to hear the latest phase in

class D technologies. Moving forward, I will then make a purchase .

Thanks Mike (@mglik)… I did not realize that the ADGs you brought over were MK2. It is great you have had time with your ARC REF 80 as well as hearing my REF 160s. 

I look forward to hearing your Dartzeel integrated when you receive it.