Need a new amplifier. Need a good match for my Audio Research LS7 preamp

B&W’s tend to be a bright sounding speaker. If you get a solid state amp you should get a FET type which tend to have a tube like sound. Here is one that should fit the bill!
http://www.avahifi.com/products/power-amplifiers/synergy-amplifiers/synergy-240-solid-state-amplifie...

I agree with yogiboy that brightness is a common comment about that speaker.

Whatever you do, do an audition if at all possible! Its very easy to flush lots of $$$$ down the loo otherwise....

I would use tubes, but because of the design of the speaker you will need a tube amp that employs a bit of feedback. This will sound smoother than most transistor amps you can find. The RM-100 by Roger Modjeski would be a good amp if you can find one, I think they are discontinued. The Cary SLM-100 or similar would be another good used choice.

Tube power is more expensive than solid state, so to get the same power I think used is the way to go. Good Luck!

How's your room acoustics? Brightness at higher volume may indicate a "live" room. Even the cheap acoustic foam is better than nothing, but thicker the better, like 3 or 4 inch. I covered Roxul panels to good effect.
I agree with the amp suggestion to the extent that it won't be as shrill as the Arcam, but the better amp won't tame a shrill  speaker and room.

agree re rom tmts.

also, maybe not any FET type but J-FET 

it is getting old and tough to find,  but a Muse One Hundred Sixty sounds like a perfect fit. 

A lively room is definitely something to be considered! The room is at least half the sound of any stereo so proper room treatment is important.

The older Classe' CA300 or CA400 had a solid, non-bright sound back when I used SS.  But the CA200 had a marginal power supply for demanding speakers. They would drive most anything and should be very cheap by now.  

To compound the issue, the ARC LS7 is inherently brighter and livelier.  I know, I had one.  That's what was so enjoyable about it.  However, it needs to be mated to a warm amp.  The Muse as timlub mentioned would be great if you can find one.  An older Classe, as mentioned, or Belles amp would work really well.  Try some MIT or Transparent cables as well.  Best.....

Beware that the LS7 needs a poweramp with at least an input impedance of 60 kOhm , normally a tube poweramp has 100kOhm , just look at the specs of the ARC tube poweramps .

If buying used is an option, the older McIntosh SS amps may give you the sound you're looking for within your budget.

Are you planning on upgrading speakers anytime in the near future? If so I’d do that first rather than trying to tame the sound with an amp that may be too warm sounding if you get better speakers later.

That said, there’s a nice Classe CA300 for sale a little above your current price target that should tame the top end a bit along with providing a big boost in power for higher volume listening. There’s also a McCormack DNA1 with Steve’s silver upgrade mods at a bit under your price target. Not a warm sounding amp -- more neutral IME -- but should provide significantly more refinement to your top octaves versus the Arcam and may well also help with dynamics and separation (i.e. less congestion) at higher volumes. This is also an amp that you could pair with much better speakers in the future and still be more than fine, or you could even upgrade amp to one of Steve’s higher levels if you want even more.

Anyway, hope this helps and best of luck.

@hansk46 .....very good point.  IIRC that would rule out the Muse.  Belles and Classe still viable options.  soix's McCormack recommendation is even better imo as you do get a more refined and neutral amp with the correct input impedance.  The McCormack is an amp that can be partnered with many different speakers.

Also IIRC, the ARC LS7 has a higher than average gain ( at least mine did ) which could be contributing to more glare and brightness especially at higher volume.

Best and keep us posted.

j200jr,
The later Classe CA-200 with the heat sinks on the side are reported to be much better than the earlier model with the heat sinks on the back because of "distributed capacitance" - caps distributed over the circuit board instead of just at the power supply (as I understood it), and equal to the replacement CA-201. There was a later version of the CA-201 that was said to be much smoother. It has aluminum "pillars" at the front corners. I had the earlier version and it was a bit coarse. Classe was said to be a good match for B+W.
You haven’t mentioned your cables so I will add that better cables could give you more clarity. Recently I upgraded my speakers and have a bit of glare at higher volumes too. Until I can demo cables I have stuck Post-it notes over the tweeters. It works surprisingly well, costs nothing and puts the fun back into listening. Good luck on your quest.
Bill

I believe the amp Ralph (atmasphere) was referring to is the Music Reference RM-200. In it’s current Mk.2 form it retails for $7995, and can very occasionally be found used (it’s a keeper!) for around $3000. The original non-Mk.2 version goes for $2000 or so. Nice amp, which Michael Fremer reviewed in Stereophile a few years ago, putting it in it’s Class-A Tube Amp category recommended components list. Heed hansk46's advice regarding input and output impedances---the RM200 is XLR/balanced inputs only, at 30kHz ohms.

I have Khartago Extreme and it's awesome and a great value. Great match too

I use a ARC D200 ss amp and it sounds great with my LS15.

Spoke with Klaus at Odyssey, and am going with a Khartago Extreme.
Pricing about the same as a lot of the recommendations.  
A new amp vs a 7-10 yr old amp.  Also gives me the option to convert to a monoblock and get another. Or just upgrade the amp even further.
Plus a 20 yr warranty??? Seems like a no brainier
Will follow up with a review.  Thanks.  After that, may see what a DAC does for the overall sound improvement