Just to balance things up a little, I think the 09TX has a few advantages over cheaper receiverts.
It has a switch mode power supply with much greater capacity than the linear supplies in the the 05/07. The latter can sound good with easy-to-drive speakers, but if you're a bit more ambitious in that area, the 07 doesn't seem to perform as well, and I'd speculate that the 09 would draw ahead.
The SC07 get 75% of the way doubling power into 4 ohms, which is typical for any good
This graph shows that the SC-05's left channel, from Multi input to speaker output with two channels driving 8-ohm loads continuously at 1 kHz, reaches 0.1% distortion at 168.1 watts and 1% distortion at 197.2 watts. Into 4 ohms, the amplifier reaches 0.1% distortion at 249.6 watts and 1% distortion at 338.4 watts.
The SC09 though, get 98% of the way to doubling power. This is the best result that I can ever recall seeing, and I've read a lot of them over 23 years. It also maintains 99% of the two-channel power into five or seven channels, which I belive is also unprecedented. These figures are slighlty better than even the Denon POA-A1.
This graph shows that the SC-09TX's left channel, from Multi input to speaker output with two channels driving 8-ohm loads continuously at 1 kHz, reaches 0.1% distortion at 200.2 watts and 1% distortion at 268.7 watts. Into 4 ohms, the amplifier reaches 0.1% distortion at 390.1 watts and 1% distortion at 523.4 watts.
PQLS is the other thing. However
, the TI / BB SRCs that Pioneer use seem to work well even with HDMI audio inputs, which may negate the advantage of PQLS. Never thought I'd hear myself say that, but I've just read the jitter test results for the SC-LX81 (SC-07) in HIFI News and Record Review.
Jitter with SPDIF input:
560ps Denon 3808A
470ps Onkyo TX-NR906
37ps Pioneer SC-LX81 (SC-07)
183ps Yamaha RX-V3900
250ps Denon 2500/AVP-A1
Jitter with HDMI input:
3700ps Denon 3808A
3860ps Onkyo TX-NR906
50ps Pioneer SC-LX81 (SC-07)
7660ps Yamaha RX-V3900
2200ps Denon 2500/AVP-A1
These are close to state-of-the-art, even with the digital audio disaster that is HDMI, and leave the Denon DVD2500 / AVP-A1HD combo in its wake. I don't think that either stereo or MCH PQLS would be able to improve much on that.
I think the problem with the SC09 may be the cost. You have to compare it with seperates rather than intergrated amps, and I'm not sure about the value. Maybe an SC07 with really good MCH power amp would be better value? I'm curious about what other people think about that.