Depending on how loud you listen, the size of the room, and the dynamics of the program material, you could certainly benefit from having a solid source of amplification. The HTR-6030, as you guessed, is not plentiful in this department. It was mentioned that the speakers are specified to have 90dB efficiency pink noise 1 watt at a distance of 1 meter. If I've learned one thing in my pursuit of audio nirvana, speaker specs are little more than a guide and are often optimistic. Just looking at their stated frequency response lends credence to that statement. They specify two frequency responses, (total frequency response / 18 Hz - 27 kHz) and (lower and upper limits -3 dB / 30 Hz - 26 kHz). As we see above independent measurements provided by Stereophile's lab indicate the FR is in fact 49 Hz / -3 dB. That's a pretty large disparity between the provided specifications and the measured performance.
Another factor we should look at is the the lower impedance at a high energy frequency as shown in Stereophile's measurements of this system. Because so much high energy content can and often does occur around 60 Hz we can assume that this will call for a lot of power for the speaker to perform it's full dynamic capabilities. For additional fun the RTi-A9 has near to as makes no difference - 50 degree phase angle at 22 Hz, so organs and other extreme low frequencies are going to call for near 4 times the current to maintain output (based on my limited understanding of phase angles).
So yeah, the RTi-A9 would certainly benefit from some good, clean, and large amounts of power.
A ~4 1/2 ohm load is not uncommon at certain frequencies in most speakers. It's 2 and 3 ohm loads that can become an issue and a majority of ported speakers are going to draw large amounts of power below there -3 dB point. The speakers I'm using have a similar phase angle at 111hz, where there is far more musical content and even male voice content, and I have no trouble driving them on a 100wpc receiver.
If the speakers truly do roll off that high (which doesn't seem right based on the reviews), and one intends to listen to music with significant amounts of content below that frequency, a subwoofer should be used. It's why we don't run the LFE through our mains and expect good results. Humans already can't hear bass very well, if a speaker is -12dB at 20hz, at a listening level of 80dB it's below the threshold of hearing. If he isn't planning on using a sub, it's definitely something that should be considered.
Not necessarily. Sadly PSUs in low to mid level receivers these days are less robust than they were even 5 years ago. You'll be hard pressed to find low to mid level AVRs that will break 22 lbs. on a scale.
As for OP, if you have a budget of $1000 or under, I'd suggest looking for gently used and well maintained separates. Adcom power amps are very good options for 2 channel requirements and have plenty of dynamic headroom to handle the RTi-A9s.
That's true, but couldn't a used receiver fit that function? You can get a Marantz SR 7400 on ebay for around $100. It's rated for 130 wpc ACD 20hz-20khz and weighs about 30lbs. IIRC it has a large toroidal transformer in it that takes up over 1/3rd of the receivers space. As someone who has previously owned one, I can vouch that it can reach painful levels of volume without breaking a sweat.
Regardless, it really depends on what sort of spl level he is looking to get. While the sensitivity doesn't tell the whole story, it still rings true that 1w/1m is what you'll get across the majority of the frequency range. Add in room reflections and you can gain as much as 3dB. With these speakers, a mere 50wpc at a distance of 12 feet would yield 98dB, an unsafe listening level. At 100wpc, 103dB. Add in room reflections and you get 106dB. People seriously over estimate the amount of power they need. Not to mention one must double the amount of power just to get a 3dB increase. If he were using them for a large dedicated home theater and listening at reference volume a case could be made for external amplification, but for his purposes any receiver that is rated at 100wpc 2ch driven 20hz-20khz FTC will fit the bill.
I stop paying attention to reviews when reviewers claim that a speaker "really opens up with large amounts of power". Either the amplifier is capable of driving them without distortion at a specific SPL or they're not. For once I'd like to see someone say it "really stops clipping and distorting the amp with larger amounts of power".
Considering he has stated he is budget conscious, if OP determines he needs more than 100wpc of power, pro audio amps would be an economical choice.
