St01, I'm afraid I don't have too much advice on the excess treble energy if for no other reason than I'm an owner of a digital EQ, so if I have such a problem all I need to do is zap it, of course. But, traditionally people do generally try to solve frequency response problems by taking a closer look at equipment matching and/or cabling and/or room treatment. I suppose I just listed those options here in order from most expensive to least. Walk near to the center of your room and clap your hands loudly. If there's a lot of what they call "slap echo" that takes more than a second to die out, then you likely could use some room treatment. The idea is not to completely cancel all reverb, then your vocal intelligability would tank, just introduce enough treatment to balance things out. If you do not hear too much echo, your existing treble energy may in fact have another (electronic) cause. But, room-wise, high frequencies are the easiest to deal with and by the time you get to the lowest frequencies things can become space-consuming, technically complex and even expensive (though arguably worthwhile). There are acoustic panels specifically for the purpose of reducing the highs (or mid-to-highs) that are sold by Audio Advisor and the like, but lots of people tend to make their own panels from common materials and save (you can probably google for some of the different recipes or try searching audio forums). Or, folks have even used a strategically placed hanging tapestry or 2 of appropriate size (if they fit in your decor). As for speaker placement, there is something called the (George) Cardas method that is especially usefull for symetrically shaped rooms (or nearly so) which you can google too. Also you may want to consider which wall (assuming you have a rectangular room) you want to place your speakers along - the long wall or the short. People always argue about which is better, but I've found it seems to depend on a host of factors other than simple geometry - room contruction materials and construction design and so on - so you'll just have to try that experiment for yourself and see, but in general if your room is on the large side, you should try along the short wall first and if your room is a bit small, your should likely try the long wall first, but sometimes you happen upon an exception to the rule. But as far as AC regeneration systems go, although I have no direct personal experience with them, I'm not aware of too many people that have tried them and have sworn by them that have also tried other power filtering options. I suppose that the real underlying problem with AC power (which itself I believe IS a legitimate area of concern) is both EMI/RFI and power supply crosstalk. Crosstalk is created whenever one power supply's resonant frequency is different from another power supply's resonant frequency on the same electrical circuit (in this case your home) - note that this type of electrical noise formation applies to ANY power supply plugged into your home(!) - any appliance, any cell phone charger, computer, any wall wart...anything that draws a residual current while off but plugged into an outlet...which any more is just about everything - not to mention all the power supplies in your A/V components themselves. The standby current these devices generate are almost as strong as if the the device were on and being used. All these different frequencies combine and then recombine to produce higher order mutiple harmonics of those frequencies...all of which tends to (severely) restrict the audio bandwidth. But, to make it short, years ago I could have made a few recommendations on moderately or budget priced all-in-one AC filters, but since I stumbled across the Alan Maher Designs products I mention in my above post I've seen no need. These products are more effective and yet less expensive than anything I've seen. This guy doesn't advertise so as of yet he hardly shows up on anybody's radar, but I'm a convert mainly because I save big and there are no sonic drawbacks, only plainly heard advantages. Hope this helps.
