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.


The AGD monoblocs intrigue me. They seem to grab quite a few listeners. "Jay's Iyagi" on Youtube gave them lots of praise.

Hi @acresverde I was previously using (and will keep forever) an Atmasphere S30 Mkiii OTL amp. This has been a very good match for the Avantgardes with a really good mid/high range. I use the high level/speaker connection into the Avantgarde SUB225 powered bass section so the ’flavour’ of the amplifier comes through. What I found with the Audions is that the bass is clearer, more punchy and tuneful which meant I turned down the SUB225 level.

I think the SUB225’s are good to a point but seem to get left behind in the music if set too loud (or with the crossover set too high).

I should add that I also have a REL S812 subwoofer (high level connection) behind my listening position which also helps with satisfying low frequency levels. The REL sub also feels much ’faster’ when connected to the Audions.

TBH I was happy with the Atmasphere amp but I am now retired and play the system a lot each day so the energy consumption, heat and cost of valves was becoming a concern. I did consider Ralph's new Class D monoblocks but I am in the UK and there is no dealer or demo available. The Audions run cool and don’t draw much power as the Avantgardes only require less than a Watt to reach deafening levels!

www.enjoy the has a short review with some good pictures of the tubes.

Please refrain from calling the glass containers 'tubes'. Mis-stating that can be very confusing to people who don't know better. They are not tubes in the true sense of the word