I'll open it up and take a look at the caps today. It's a little disheartening that Marantz is using cheap caps and/or not cooling their products adequately. This thing runs much hotter than my Sony and Denon (I know Denon and Marantz are built in the same factory, but the Denon at least has a couple of fans under the amp sinks). Marantz used to be the crème de la crème!
My old Sony Pro-Logic receiver from 1991 is on its original caps and still going strong as a retro games console/computer amp. And early Dolby receivers weren't exactly high quality products, at least when compared to the stereo-only stuff of the day.
I don't want fans humming in the background. I want the vendor to use enough heatsink and airflow space to cool passively. So far I've not found a Yamaha that wasn't well designed although I haven't shopped their offerings in the past 4-5 years.
In my experience, stereo receivers usually do better because people expect a home A/V equipment footprint that's typically far too large for a 2-channel unit and a bit too small for a multi-channel unit, meaning you end up with a cyberpunk diorama of either rural America or the Kowloon Walled City. The latter isn't great for heat dissipation.