Quite honestly, I would bypass the ATI Amps completely and go straight for the Hypex or Purifi Amps. Even the straight Hypex Amps as available through Buckeye or VTV rate very highly in almost every metric that is valued. Some of the other companies (Nord, Apollon, etc.) use the Amp modules and SMPS still, but include a custom input buffer stage: these still measure amazingly well but cost more for the extra circuitry. I am uncertain if their is a "sound quality" associated with this added circuitry, however, the standard Class D versions from either company are known to be very clean and transparent.
The difference you get with ATI's implementation of the Hypex Modules is that they are using a linear power supply. Their Class D Amps are significantly heavier than the SMPS versions using the same modules.
Does the linear power supply in the ATI change anything?
I can't tell you that.
There is this review and associated thread you can explore:
In market for a powerful 200 WPC amp? ATI has you covered with two completely different technologies . The AT4000 class A/B and the AT522NC Class-D amplifiers both fit into the 200-watt sweet spot and both have surprisingly similar specifications. The AT500 series is 25% cheaper and up to 50%...
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