Yes, true 8ohm speakers (that don't have difficult phase angles, and or low impedance zones) are often very easy to drive and cheap amps will rock them.
There are a million ways to spec an amp and why different products are speced the way they are is impossible to condense or know.
As I mentioned earlier it takes DOUBLE the power just to gain 3db of output. The differences between 80 and 100 and then 100 and 150 is not very meaningful and is waste of your attention.
I posted a screen shot from part of the data sheet specs to your amp in a previous post.
Your amp is fine for now. It is THX certified which does actually mean something. It can handle 4ohm loads. You are only driving 2 speakers. They even rate it's dynamic power in 3ohms, meaning they are comfortable with you driving it hard.
Nobody here actually can really tell you that your AVR is weak. I honestly don't think it is. I am actually impressed with it's specs for the price. Yes it would be nice if actually doubled power from 8ohms to 4, even again down to 2ohms but almost no amps can do this.
Don't waste your cash on a Rotel. As much as I love ultra low distortion amps like the Hypex stuff folks have mentioned it will be a waste, 'me thinks. I would buy a super powerful Crown amp
IF the AVR is not enough. Buy the Crown XLS 1502 or the 2002 and never worry about power ever.
DriveCore™ 2 Series power amplifier — 375W x 2 at 8 ohms, 2,100W x 1 at 4 ohms bridged
www.crutchfield.com
DriveCore™ 2 Series power amplifier — 300W x 2 at 8 ohms, 1,550W x 1 at 4 ohms bridged
www.crutchfield.com
Yes, they really make huge power and yes they sound great and they are efficient as well. They also almost double power from 8ohm-4ohm-20hm so you will never be short of dynamic capability. Don't waste cash on anything else "audiophile/audiofool' unless it has been reviewed by ASR and proven to be worth the money.
Also remember that your amp is really only running out of power in the bass, manly because the ELAC speakers are low sensitivity. Something like the 590's will be easier to drive to the same levels, it will be easier not harder due to the speaker having much higher sensitivity. It will take about around 1/4-1/2 the power to make the same SPL. Meaning your amp will be floating along. The larger speaker voice coils will also not be as hot meaning that compression will be potentially much lower.
In the meantime I think your amp will crush very well with something like the JBL 590's or the aforementioned KEF R11.