What is your favorite Class D amp?

I moved from Primaluna HP to Bel Canto's 600's and did not like the end result.  In my system / room music had no life.  I really tried to make it work but after 8 months I sold and started over. I moved from Bel Canto to AGD Audion.  Everything was back, sound stage, warmth, with a llittle increease in detail, light weight and little to no heat.  All in all it was exactly what I was lookng for.  Like @marco1 I use a tube pre - Cary SLP 05.  I've never heard Atma-Sphere Class D but, from my perspective, AGD and Atma-Sphere is where I would focus.  I would not heistate to buy used but I rarely see either amp for sale used; may say something!  Good luck with your search!

TEAC ant their upscale sister ESOTERIC (Japan)
Top models have dual-mono design including power supply, and the best class D circuits from ICE Power (Denmark) and Hypex (Netherlands)
The two TEACs I own sound impressive for such a compact design.
 

I wanted the efficiency of class D for a large speaker system, but without the stereotypical sound character of class D (sterile, clinical, lean, or glassy). I did find the latest Hypex and Purifi options appealing due to their modular designs and price/performance ratio. The Hypex Nilai is well regarded, but I was impressed with the flexibility of the Purifi Eigentakt platform, which allows third party designers to engineer their own buffer stage, and it is here that the overall character of the amp can be individually tailored to a significant degree. 

Having seen a YouTube review by Thomas & Stereo (of Galion Audio), I took a chance with the VTV Purifi 1ET9040BA monoblocks with the Sparkos designed vacuum tube buffer with Weiss op amps. I can vouch for this combination delivering analog-like character and a bit of vacuum tube imaging, but without softened transients or being syrupy. I don't see how anyone could audibly distinguish this from a class AB amp. The same configuration is available for the smaller stereo 1ET6525SA, which is relatively economical. For tube lovers, I believe combining this configuration with a good tube preamp would certainly be worth a listen.

@goleksiak - Congrats on the Von Schweikert Ultra 55.  Looks like a real keeper.  The Stereophile review said that the minimum impedance was ~2 ohms. Based on your comments it appears that the AGD Duet has no problems with that at your volume levels.

Enjoy!

@reavesdc I've never had an issue. I asked Grok about Duets with 2ohms loads: 

Key Performance Expectations with 2-Ohm Loads:

• Power and Current Handling: The Duets can deliver peak currents exceeding those of many traditional Class A/B amps in this power class, often estimated at 600W+ into 2 ohms based on their doubling pattern and GaN architecture. Reviewers note they "anchor perfect control of image and musical energy regardless of amplitude," even with speakers featuring complex impedance curves.
• Sound Quality: Expect retained transparency, speed, and SET-like warmth without compression or distortion. Bass remains tight and extended (no muddiness), mids gain lifelike body, and highs stay smooth and detailed. They excel with "difficult loads" like those with upper-bass impedance dips, outperforming conventional Class D designs in grip and effortlessness.
• Stability and Efficiency: No thermal issues or shutdowns, thanks to >94% efficiency and minimal heat generation. They're praised for driving "any demanding loudspeaker" with authority, similar to higher-end AGD models like the Solo (rated for >70A peaks into 4 ohms).
• Limitations: While robust for most high-end speakers, extremely reactive or phase-shifting loads below 2 ohms might push limits at ear-splitting volumes, but this is rare in home audio. They're not ideal for massive horns requiring 1,000W+ bursts, where the pricier Solo would shine.

In your high-end system, pairing Duets with 2-ohm-dipping speakers would likely yield punchy, fatigue-free playback—far better than amps that falter here. For confirmation, AGD offers in-home trials to test with your specific setup.