I have a X4000 (currently in closet as a backup) that I used for 4ish years. It was connected to 2 different speaker setups (both low and high sensitivity) in 2 different rooms both with limited and very good ventilation . My speakers were always set to small with an 80hz for front and 80-100hz for rears depending on the speakers. Audyssey was always used . I listened at -25 to -15 for movies.
My X4000 ALWAYS ran hot and would quite often go into protect mode regardless of which speakers I was using or with limited to good ventilation.
Running a small fan did help but did not solve the issue for me. My solution was to buy an external amp which did solve the heat problem and I never had a shutdown again.
I have used Onkyo, Integra, Denon, Sony and Marantz receivers in the past from entry level to upper range. The X4000 and the Integra were the only receivers I could get to shutdown without actually trying to. The X4000 was the replacement for the Integra so I was not exactly a happy camper with the new receiver in that regard.
That is indeed weird. I bought the little AVR-1912 for my daughter quite a few years ago and I could listen very loud without any shutdown, never happened....
I think there maybe something wrong with the protective circuit setting in your particular unit, not necessarily all X4000.
Its predecessor that has very similar specs, was benched tested by S&V:
https://www.soundandvision.com/content/denon-avr-3312ci-av-receiver-ht-labs-measures
It was able to do :
-Two Channels Continuously Driven, 4-Ohm Loads, 202 watts at 0.1% distortions, and 225.5 watts at 1% distortions.
- Five channels continuously driven, 8-Ohm Loads, 82.9 watts at 0.1% THD, and 103 watts at 1% THD.
The X4000 should be able to do the same, or slightly better.
