new at this...which amp?

Snofun3.....by front end I suspect you are asking about the source? I have a 250.00 Denon cd player and usually listen to music through Comcast cable's digital music stations. I hear no difference between them. Having said that, you are probably thinking I have a tin ear. Probably right about that. Now consider how harsh my system must be if I can hear it! I am going to see if my local high end store will let me audition interconnects and a bigger amp. If that does not do it I will move on to fixing the room. I want to thank each of you for your help.

source is a real contributor to your problems. I used to have a $400 denon cdp and it practically killed me. Try a used rega planet. It's worth it. Cables and amps matter as well, but garbage-in, garbage-out!

1) The room
2) The source
3) The interconnects
I would address all three. You don't need to better amplify what is already compromised source material.
If the system has sounded harsh in three different rooms, I'd still begin by treating the room. With $2500 to spend, you can do a lot with the room, the source, cables, etc. Once you've done these three things, please follow-up here. I predict you will be stunned by the improvements. And I would not start with the amp, FWIW.

Your amp should have more than enough power. You should really try to borrow gear and swap only 1 piece at a time until you find the culpret. If everything is sounding harsh when played loudly, you can eliminate the cd & cable (compressed music usually sounds flat, not bright).
Borrow a stereo only amp if you need to just to run the right and left channels to compare to the adcom.
Personally, it doesn't seem to me like your system is balanced. You have shorted yourself with not enough spent on the sources, nor on the cabling. What speaker cables are you using, do you have a line conditioner?

I don't think power is your problem. Your speakers are rated at 89db with 1 watt which is about average. 150 watts should be plenty unless you are really cranking it up. It's more likely that you are amplifing crap up stream, so look there first.

I wouldn't give up quite yet on your Adcom combo. Adcom is usually near the top of the mid-fi range of gear. I am sure there are numberous reviews that should confirm/deny the quality of your gear.

Your DVD player and interconnects would be a better place to start than swapping amps. 100-200 bucks/pr for good interconnects might help a lot. Stay away from silver and go with a well reviewed smooth sounding copper interconnect. A decent digital cable may help as well. A new DVD player would be the next move. Look for something that is well reviewed for sound quality which is sometimes only brushed upon.

One thing you could be hearing is the compression inhearent on DVD recordings. The quality of DVD sound will become worse (compressed, muddy, flat, etched) as the complexity of material and channels in use increase. As you improve your system, the problems are magnified.(This is the death spiral of hi-fi) Use both multi-channel and simple 2-channel material for testing. Complex multi-channel material can hide problems and confuse your mind about what really is going on. Use material that you are really familiar with.

I found this quote on the net from another B&W NT9 speaker owner;

"I had to sell these speakers due their brash, hard and uncomfortable sound. i tried changing other components to see i could take some of it away, going to the length of buying o 300 watt krell, but they fundamentally stayed the same. there was alot i liked about them - presence, detail, soudstage focus to name a few, but they were not easy on the ear, especially at higher volumes.
i used a CDM-7Nt for a while, which was a much more balanced sound."

Sound familiar?

You might be fighting an up hill battle with these speakers. Armed with this bit of info, you might try swapping your rears to the front and see if you draw the same conclusion as above. Do an A/B test with music and movie content with front 2 or 3 speakers only. If they have the same mid-tweet combo there may be no difference save for the bottom end. If this does the trick, another pair of 7nt's might be the solution.

A few more easy tips:

Leave your amp on 24/7. Most amps sound better (more open) if they are on for more than an hour.

Speaker "break-in" may be an issue if they are new. Make sure you have lots of hours on them.

Plug your amp directly in the wall. Eliminate cheap power strips!!! Get a decent power conditioner for your DVD and pre-processer. These components need clean filtered power for SMOOTHNESS. Amps need current for dynamic power. You can always use a power conditioner even if you upgade components later.

Try this test. Plug-in only what you need to make the system work (eliminate power strips) and see if that makes any difference.