You have the right idea. Any receiver will have limitations... just as any amplifier will have limitations. I guess I just assume if one pays enough money for a set of Electras, one will pay for suitable electronics as well. Unfortunately that is not always the case...lol
What the customer purchasing the electronics needs to realize is the output transistors of the amp or receiver will be a limitation on the output, but that is not the only limitation...
The power supply is also a limitation as it must be able to provide enough power to the output stage. In an Amplifier Unit, the power supply only must power the amplifier. But in a receiver, the power supply has more tasks and is very often undersized in non-top-of-the-line receivers. When the power supply is undersized, all channels will not be able to provide the rated max power output at the same time, and this is a time when clipping and speaker damage may occur.
An example of an Amp where the output transistors being rated for one value and the power supply is rated less is the Anthem PVA-7 which I use in my system. Here, with all channels driven, the max output per channel is less than the max output if one one channel is driven.
PVA-7.png 5k .png file
Usually receivers will be even more hindered. A Denon AVR-E200 is rated 165 Watts (Maximum Power Output Per Channel), but that is most likely only one channel driven and very noisy... I would not trust this receiver with high quality speakers...
AVR-E200.png 5k .png file
Disclaimer for the following section:
If something is in question, contact the manufacturer or someone who has actually tried it to ensure it will work... I have not tried any of these... The following lists data from websites, but also includes my thoughts and opinions, so I could be wrong...
Although I would think they should be able to handle the dipping load at specific frequencies, the Anthem MRX Receivers are only rated at 8Ω and the Denon AVR-4520CI is only rated to 6Ω. If these were to be used and driven hard (read as played loud). If the speaker rating is 8Ω, I would not worry about a momentary drop to 3Ω at specific frequencies... But, if the speaker is rated 4Ω, these two receivers may have some problems and the customer should contact the manufacturer to ensure it will work...
The Pioneer Elite SC-79 & 77 have ratings at 4Ω, but at 1% thd and the NAD T 787 is also rated at 4Ω but distortion is not listed at 4Ω. So these would be able to drive the speakers, but due to distortion, one may want to go with separates with better ratings if they will be played loud...
Thinking about my earlier though, this is probably a moot point since anyone who pays for Electras would probably pay for at least entry level separates. But on the other hand, I have read reviews in the past comparing some of these high end receivers to entry level separates with near equal results. As such, these receivers may be something to consider for some people, especially if they will not be driven to full volume.
I would think when dropping down a Focal Series to 700, 800, and maybe even 900 series, the sonic loss of these receivers compared to separates probably would not be detected or may be very minimum compared to room reflections and other sonic impairments.