I've had some time to get the thing unboxed, opened up, placed in its final spot, and I even managed to get two channels up and running with some old (quality) RCA cables. I have a very small buzz coming from the speakers, but I have to put my ear up to them to hear it. When I remove the RCA input from the amp, the buzz goes away, so it is not indicative of a noisy amp, but either a noisy preout on my Denon or the RCA cables picking up some garbage.
First impressions....keep in mind I'm no audiophile, but I have a nice system and enjoy it greatly! I was actually surprised to find that the Power5 and my Denon AVR-5800's amp section are very similar. There is a small difference in how the low end is handled, the bass does indeed seem quicker and more responsive. If anything, the Denon did have a bit of harshness to it when pushed, where the Power5 seems to be easier to listen to at higher volumes. Most likely reduced distortion coming into play. I didn't get to really push it tonight, as it was late and didn't want to wake the kids. My goal of at least maintaining the sound quality I had before (when I eventually sell my Denon and replace it with something newer) has been met. With my first foray into the world of dedicated amplification, it wasn't earth-shattering by any means, but then again, changing out speakers and treating the room will probably offer more noticeable changes. My speakers are fairly efficient, 90dB/W, 8ohms. The AVR-5800 provides up to 200Wx2 in two channel mode, so don't think I'm equating the Power5 to any mass-market receiver. This was Denon's flagship 8 years ago....and priced at almost 4k back then.
The Power5 is built very well, by the way. See the attached pics. They really tried to design out noise wherever possible. Each module is enclosed in its own cage. The two big cages are the 500ASP modules. The 3 smaller cages that are located under the big red board toward the back of the unit are the 500A's.
The small yellow board near the AC input on the back of the unit provides AC to DC rectification for the controller board (smaller red board) that houses the NHT ethernet circuitry.
The thin green board in front of the yellow one is basically a filtering circuit (LC) to keep high-frequency noise from entering the ICEpower modules. The AC is fed from that board directly into the two 500ASP modules.
The 500ASP modules are bigger than I imagined. They have four caps in each module, each one is 1200uF for a combined total of 4800uF per 500ASP. Think of these as power reservoirs for transient effects. The two modules DC lines (50V and 80V) are fed into the larger red board at the back of the unit. That board handles the DC bus, connections to speaker outs, and signals from the input connectors. Notice the three large caps on that board. Each one is 4700uF. It doesn't take much of a leap of faith to see that they tried to mimic the on-board capacitance of the 500ASP modules and have similar capacitance available to each of the remaining 500A channels. I think this helps bolster the dynamic power available to any channel (300W into 8 ohms).
By the way, I ohmed out the speaker connections for CH1 and CH5 and verified they do indeed run to the 500ASP modules.
So, there you have it. This amp has been very well designed, well built, and sounds great. Not bad for $1200! Did I mention it stays cool?