I'd have to think about what Squishy Tia is saying some more. I wouldn't think lack of separate power supplies for highs and lows would matter any more than lack of separate power supplies for each channel would matter?
It does matter. With but a single power source, you're just effectively bi-wiring with each speaker getting its own XO before the output stage. Bi-wiring is not bi-amping unfortunately, since as I noted before, the power supply is a single unit to both parts of a speaker.
My Adcom example holds true as well. Each of the channels has its own power supply internally, thus both the lower and upper array can benefit from the full 200W for each channel driving them respectively.
My Adcom is setup as the Left channel driving the bass array on my RTi-A9 and the Right channel driving the mid/tweeter array of the same speaker. I have one Adcom for the left channel, and a second for the right channel. The benefit of this setup instead of just using the L/R channels on Adcom1 to drive the bass arrays on the L/R A9s (respectively) and the L/R channels on Adcom 2 to drive the upper arrays is that there is zero crosstalk
. None. Zippo. Zilch. Nil. Nada.
Both channels of the same Adcom amp do have slight crosstalk, but since only that one Adcom is driving a single speaker, both the lower and upper array receive the exact same channel info because the channel info is incoming via a Y-Splitter from the L or R pre-out of my HTR-5860 into the Adcom, with a Y-Splitter on each of the L/R to feed the respective amps.
While this does mean that I lack an external XO for the upper and lower arrays (and thus lose a bit more energy to thermal dissipation than if I indeed did have an EXO), the signal remains identical within each speaker's array, and the other speaker's channel info never gets to crosstalk into that amp. The result is a very
open sound stage, and with both the lower and upper arrays having access to independent 200W power supplies, I get a total useable power of 400W per speaker.
This, sadly, is not something any AVR will be able to do, even the Onkyo I mentioned above.
If you're going to bi-amp, use external amplifiers of the same design/make. And don't let audiophiles tell you that the method I'm using isn't a true bi-amp. It is, as it use independent power supplies for each array within a speaker. Both EXO and IXO (external and internal crossover respectively) methods are true bi-amp when independent power supplies are in play. The difference is in thermal dissipation (lost energy). EXO is more efficient, IXO is more flexible and does not require modding the speakers if the speakers have their own internal crossovers as the A9s do. Just make sure your amps are identical - you don't want to have to screw with gain variances between channels.