I had an Onkyo 876 (and its later derivative the Integra DTR70.4) and I can vouch that they could and did drive 1.6ohm speakers very well indeed...
However I've seen no indications that the current X3800/X4800 models have the type of capabilities that the much lauded AVR3805 had... I believe the current equivalent to the 3805 is probably the 6800....
For the nth time, any such AVR can drive 1.6 ohm speakers, it is not a black and while thing as it depends on the impedance and phase angle vs frequency, sensitivity across the audio ban, seating distance, and your required spl.
Questions for you:
- why you keep making generalized statement such as xyz amp can drive 1.6, 2, 3, 4 ohm load?
- if I my seating distance if 2 meters, speaker dip to 1.5 ohm but only at 150 and 200 Hz, sensitivity is 92 dB/2.83V/m, and the loudest spl I ever listen to is 90 dB peak, then why can't the 3805 drive my speaker?
With due respect, repeating your kind of general statement does not make it true, and it might confuse people who actually don't need to spend money on another amp and ended up spending it on one when they could have spent money on something that counts in terms of sound quality.
I would strongly recommend a science based forum such as this, to avoid making generalized statement that could well mislead other members (unintentionally and/or unknowingly obviously) and/or help create/spread/sustain audio myths and/or misconceptions that we already have no shortages of in this hobby.
Sorry about being critical, you have been among the few that I know are very knowledgeable and have been offering helpful advices to others including me, just wish you could avoid generalizing, sometime.
If I am wrong in what I am saying about the amps vs impedance, phase angles, sensitivity, distance, required spl relationship, please do enlighten me, with facts and figures, or other objective views (link would be great). To avoid being sidetracked, I would avoid the effects of "protective schemes" and any subjective reviews for the time being. For example, if an amp has protective scheme that could sense load impedance dropping below certain limits, would actually switch to some sort of "limp mode" (or even shutdown right away) reported on forums such as ASR, on perhaps one of Onkyo's, then of course all bets are off.
Also, your reporting of the issue with your 1.6 ohm dip speaker that you posted the curves were a specific one that I believe something else was causing it, not just the current demand that you got fixated on, and on that one, I have said enough so we agreed to disagree on that one, though I am sure if I were there, I would most likely be able to discover why a seemingly more capable amp could not do it while you other seemingly weaker amp could do it under the specified conditions, and no, I am sure both amps had the current capabilities under those conditions.
Again, not going to repeat things we stated in that thread, suffice to agree to disagree on that one. I am mentioning it now only because that example is too peculiar and too much unknown, for it to be used and example to support claims made.