If you have the skills (though you just really need soldering skill and some ability to drill holes in metal to put a kit together) you can checkout the Mod86/Par86 amps on DIYA - rough total build cost is $400+ from memory, definitely under $1K for 2 channels... It measures very well and the designer is very active in the product thread. Seems to get good feedback reviews too.

They would work rather quietly.

In other news - blew the tweeter on my LS50, expecting a replacement driver next week. Will be building a Modulus-86 amp for my LCD-2's.

Ain't the ls50 full range?

Also 10w depending on sensitivity of speakers and listening habits of person and types of music. It won't give person lot of headroom for cranking out but, again overall depends.

I know someone audiokarma very happy driving their kef ls50 with a crown xls 1500. I own a crown xls 2500 myself. Actually was more impressed with it then I thought it would when I used it for month driving my large altecs for a month before deciding using it as a sub amp driving large and heavy jbl dual 15" 4648 theater bass bin as dedicated sub.  I use a big crown CE2000 now driving my mains which traditional class a-a/b amp but, thought the class d xls2500 performed 99℅ just as well for full range use. They're just very picky on some preamp/mixer paring between the source and amp.

I like the crossover features and they do work flawlessly as well. The peak limiters do protect your speakers very well too cause it has voltage tracking and will limit its current output when it senses your speakers start to send clip signal but, can easily turn the peak limiters off for consistent full output if needed. They stay super cool too even when pushed to beyond max output and will not shut down. That's why I like them driving heavy loads like subs. I like them personally and not badly priced for their performance. Them weighing only 11lbs makes them easy hual around. I use nothing but, pro stuff for even home now but, still have share of favorite vintage home stuff.

How did you manage to blow it up?

1.Unplug inputs, amps starts to oscillate in ultrasonic frequencies.
2.
3. Order new driver.