[B][/B]
I have a tv room that is 12 x 12 x 24 >open space to the kitchen. My main focus for the amp is 50% tv/dvd watching and 50% CD / SACD listening. Whatever amp I purchase it's for the long term. Will I hear a big sonic difference between the 7125 and the 7500 with speakers I have and room size? All I care is about buying the right amp for the most efficient use of my speakers. FYI. The RTi 8's and the CSi 5 center speaker can handle up to 250 Watts per channel.
Thanks for your thoughts.
Kirk

1) the difference between the two levels of available output is about 2dB.

2) your speakers are moderately efficient with a sensitivity rating of 90dB.
...(hopefully that is the truth)

3) the 7125 is weighs less for shipping purposes

Based on the above, I would try the 7125 first. If within the 30-day trial period you find the 7125 is not quite enough and you wish to trade-in for the 7500, you’ve lost less in shipping that if you tried the 7500 and wished to trade-in for the 7125. Of course if you go with the 7500 first, you probably won’t want to give it up. I chose 200wpc because my speakers have a sensitivity rating in the mid eighties, so right away you’ll have more overall acoustic loudness available at 125wpc that I do at 200wpc. Which brings up a point in favor of the 7500 if you are going to keeping whichever amp you choose nearly ‘forever’ – if you ever change loudspeakers to some that are several dB less sensitive, you’ll have power in reserve to drive them harder just to achieve about the same acoustic level as a 7125 matched to your current Polks.

Rather than trying to match a speaker’s power rating – a power rating of 200 watts means it could stand that much input for a very short duration without destroying itself and likely you wouldn’t want to exceed a continuous feed of more than 40 or 50 watts anyway as this might cause a slow buildup to an overheat condition – the 7500 allows a little more headroom for spikes to cleanly be reproduced, so that when you are listening loud and detailed spikes occur, the sound remains very clean sounding. That is one of the distinctive differences I noticed between my 100wpc receiver and Outlaw separates when I upgraded – the Matrix was a hot DVD at the time and the gunshots were quite clean and crisp sounding via the Outlaw gear while ‘mushy/hashy’ through the receiver. If you forsee keeping the Polks as long as the amp you purchase, then, because the speakers are moderately sensitive, the 7125 will be cruising on a small percentage of its overall capability and you'll have that 'clean' sound from the 7125 as much as from the 7500. Additionally, with the 7125, you have the opportunity to easily either go to 6.1/7.1 later on or bi-amp your mains.

And then there is this: if you do wish to buy a newer processor/amp combo in the future, which combo would be easier to sell, the 990/7125 (a 7.1/7.2 system at 125+ wpc), or the 990/7500, (a 5.1/5.2 systen at 200+ wpc)?

Bottom line: there is no clear winner. The deciding factor may be the finer points of your current priorities and your best guess about your listening future.

In terms of other specs that are actually discernible to a listener, does the 7500 have any real advantage over the 7125 apart from wattage?

I'm thinking I could go with the 7125, buy two more Boston Acoustics Micro130xs and go full 7.1 for a little less than the 7500.

Based on the information available at the BA web site, and your post of April 17, 2007 , if you’re going to stay with those speakers for a good while to come, I’d opt for the 7125. If the BA information is to be believed, your mains are quite efficient with a sensitivity rating of 93dB. While the 130x’s are 3dB less sensitive, they are still considered to have very decent sensitivity. Your system running at 12-25 watts would sound as loud as mine running at 100 watts, which gives you more dynamic headroom at 125wpc than I have at 200wpc. Also, because you are allowing a subwoofer to handle the most power-hungry bass duties, you don’t need to push as hard in the amplifier sections.

So try the 7125 in 5.1 first. If you are satisfied with the potential cracks in the walls, the shattered glass and certainly the ringing ears that might result at 125+wpc, then expand to 7.1. If you decide that you really need cone-tearing, coil-meltdown capability, then send the 7125 back before buying two more 130x’s and get the 200wpc capacity (for which you appear to have a hard time letting go).

I agree with bestbang4thebuck on the approach. Start with the 7125 and see if you're happy with its performance in your setup. If you are, keep it. If you're not, send it back and get the 7500.

I started with the 7125 as a potential upgrade from my Classe CAV75 driving my Martin Logan reQuests, a difficult to drive speaker. It sounded a tab better but still sounded compressed, which was my long standing issue with the CAV75. I was able to do a back to back between the 7125 and the 7500 and there was a dramatic difference. The 7125 went back and I'm very happy with the 7500.

I guess headroom, reserve etc makes a difference. In my 4 ch/stereo room I was driving the Crown ES224's with Crown DC300A's as I always wanted lots of reserve.

Of course switching to the 755 made a big improvement.

dixlon,
I have the 7125 matched up w/ some 90dB efficient paradigm 60's.
I have no problems driving them hard if i want. My living room open up to front hall - family room behind and dinning room off to the side. Plus i have vaulted ceilings.