Agreed, but to some, it may be a matter of principle, not "audible" or not. For example, many Denon ex owners would not buy the X3800H not because they thought the lower SINAD would sound audibly worse than their older models, but just did not like the fact that Denon picked a DAC IC that clearly has much worse specs than the AKM one that they had been using for a few years and had good bench measurements. Marantz owners might not mind as much as many of them bought in to the marketing info about the so called Marantz sound.
With Onkyo's "limp mode", it is the same thing, more about principle though in this case it is worse because it is actually quite possible that some owners might actually been affected by it without knowing it audibly because even if they had the unit running in limp mode, the lower rail voltage's effect even if audible, may not be noticeable without being compared in quick AB tests using media contents that have good dynamic range, etc..
