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.


Hi, I already have my MK3 upgrade from my Audion. I'm in the burn-in phase, it will take about 25 hours and I enjoy the sound of my Audions. I wouldn't know how to discern now between the sound of my Mk2s and this new Mk3. The memory of a fish has those things, and I think it is essential to wait for the burn time that Alberto recommends of 150 hours to make a serious comparison about the sound between both tubes. Beyond that, I'm really liking the sound of the Mk3, but I also really liked the Mk2. At this point, my question is which preamplifier would be recommended to use in my system. I try to explain the complexities of it: I have analog sources that require the preamplifier to have a line output and RCA and XLR inputs. Two digital sources that require XLR inputs. So it is necessary for the preamplifier to have various inputs and outputs

I am running a Primaluna 300 evo pre, which sounds fantastic. You would have to get the 400 for the balanced outputs.

@mbmi I have 2 pairs Bose 901 Series 1 & 2’s stacked for my Surround Channels powered (@4Ω) by a 3 Channel custom GaN FET made by me Orchard Audio Ultra (500WPC) Amplifier.

BTW....Yes GaN chips are used in power supplies as I humorously mentioned in my Video.

. Alberto recently got into a battle of words with Ralph of (I stayed out of it - I’m on Ralph’s Karsten’s side here). I’ve heard Ralph’s GaN Amps on a pair of PS Audio FR20’s and they sounded fantastic. I never got to swap in Leo’s Orchard Ultra Amp cause the dude sold the FR20’s !! At 40% of what he paid for them !!!

I think Jeff B still has Ralph’s Amps. Not sure. If anyone can make a GaN FET Amp sound like a tube Amp. Ralph is the Man !! But Leo’s Amps sound amazing with a Tube Preamp in front of it (just ask Zeos).


Thank you very much for the recommendation. I have not been lucky enough to hear Primaluna, I know that it has good reviews and the price is reasonable (just as the prices of HIFI equipment have been set). In addition to the Primaluna, have you paired the Audion with any other preamps?

After several weeks of use with the Audion updated to MK3, I am very happy with the sound, it has been a worthwhile update. Congratulations to Alberto for allowing this equipment update system. It is a pity that in Spain there is no representative from whom you can request proof of the previous Alto. Now my audio distributor has let me try a solid preamp from the German brand Trynity and it gives a good sound, but I think that before making any decision to purchase the definitive preamp for my system, try a good tube preamp. I think Jay's uses Allnic with his Audions.