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.


My recently purchased Audion MK111's took about 50 hours to start really singing.

They are fronted by a well broken-in Primaluna EVO 400 tube pre-amp. This pairing seems to be working very well. Hearing things I had not heard before and having fun again.

I would like to take a moment to add my experience with AGD, The Audion's in particular, and my personal experience with Alberto Guerra, who is AGD's Principal designer/owner.

 In 2022 I purchased a second hand pair of The Audions in the matte grey finish, with the MK II tubes. The speakers that I would be driving them with are the Legacy Audio Aeris, which are rated @95 db at 4 ohms. They have built-in powered subs, so the Audions would thus be only required to power the mids/HF drivers...So I felt confident that the Audion's 170 watts at 4 ohms would power the Aeris adequately, even though prior to the Audion's I was using Legacy's own iV-2 Ultra dual mono amp, rated at 1000 watts per channel x 2 @ 4 ohms.

Once I received the used amps, I contacted Alberto to have the remainder of the amps warranty put into my name. We spoke at length on the phone, and Alberto could not have been more pleasant to deal with.

Upon hooking up the Audion's to my system, I must say I was absolutely stunned at their performance! I have been in the hobby since the mid 70's, I have attended 20 years of Las Vegas CES, and I have had the pleasure of hearing many a satisfying sound system's in that 20 years. Over the last 45 years of owning and building my personal 2 channel rigs, I have had the pleasure of owning speakers of all designs from dynamic, electrostatic, horns, bi-poles, di-poles...and just about every kind or type of amp: Solid state, tube, class A, Class A/B, and class D.

In my opinion, in my system, and to MY EARS...The Audion's provide me with some of the midrange tonality of the best tube amps I've owned: Audiopax Model 88, which powered my Avantgarde Duo Omega's like a dream! The Audion's soundstage/image BETTER than any amp I have owned, and providing me with all the slam and dynamics of the best solid state amps I have owned.

Late in 2023, Alberto contacted me and asked if I would be interested in the new MK III "tube"? After hearing his explanation of the improvements in the new design, I decided to give them a try. Holy Moly! Another home run hit outside the ballpark by AGD! I did not expect to experience the improvements that I heard. It did take awhile for the new "tubes" and the circuitry to "settle-in", but when it did, the smile was a mile wide! It wasn't long after that I was hearing the full impact of the Mk III upgrade, that I contacted Alberto via phone call to tell him just how much I was enjoying the amps/new tubes. For a man who is apparently a "One Man Show" as far as being the company President/Designer/Builder/Shipper, etc. he very freely gives his customer's more than ample personal time via the phone. I told Alberto that these amps were my "Desert Island/take them to my grave/last amps I'll ever want or need"...EXCEPT...In the perfect world, I would LOVE to own the polished versions. And I'll be damned if Alberto didn't have a card up his sleeve to make that happen too!

So here I sit, with the latest Shiny/Beautiful Audion's with MK III tubes, and in my 68 years of owning and building pretty damn nice 2 channel music systems, I can honestly say, that I have NEVER owned such a musically satisfying system...EVER! I firmly believe these amps are one of the very large contributions to that statement. I would wholeheartedly encourage anyone who is curious about the sonic benefits of AGD amps to audition them. Life is short...but these amps will make you want to live for eternity!

(Oh, and for the record, I really like the LED glow of the GAN tube, I think it is part of the physical beauty that matches the audible beauty! Just My 2 cents)