the best way to describe them is 'accurate.' i don't know what you mean by sounding 'british.' i've heard lots of english speakers and i don't really think they sound very similar. (linn, rega, naim, tannoy, atc)
i'm not sure what kinda info you want, but here's a list of plaves that *only* use atc equiment. just to skim over (taken from their website)
"Sony Music Studios, New York; Kate Bush; Warner Bros, Burbank, CA; Dairy Studios; Polygram Wiseloord Studios, Holland; Sain Records; Lenny Kravitz; Whitfield Street Studios Skin; (Skunk Anansie)Mute Records (Depeche Mode, Erasure); K & A Productions (Naxos); Todd AO, USA; Pioneer Optical Disc (Barcelona); Nick Whitaker (Internationally Renowned Acoustician); Telarc; VTR TV Production Company;
Ground Control, LA; Paramount Pictures, Hollywood; Angell Sound, London (5 Studios); BBC - UK; Royal Opera House, Covent Garden; Lightning Seeds (Ian Broudie); Sydney Opera House; Pink Floyd's Studio & Dave Gilmour's Home; Royal College of Music; Jarvis Recording Studios, NY; Birmingham University; Dep International; Essex University; Nimbus Records; Bristol University; John Kurlander; University of Surrey (Francis Rumsey);Ian Anderson; Ronnie Scott's Jazz Club; Manor Mobiles; Lou Reed; Beacon Studio (Dublin); SBS Television, Australia; Hans Zimmer; Lansdowne Recording Studio; Karl Wallinger World Party; Greg Walsh (Producer Paul McCartney, Tina Turner, Elkie Brookes); Albert's Music; Angel Studio, Islington; Peter Walsh (Producer Stevie Wonder, Peter Gabriel, Simple Minds, Pulp); Oorong Studio, N.Y.; London Post; James Guthrie (Pink Floyd, Toto, Chicago); Enya; The Tate Gallery; Thierry Allard, Bruxelles; Bob Ludwig Masterdisk; Boogie Park Hamburg; Bruce Leek; Bruce Dunlop Assoc., London; Vogler Audio Media; Prince Sufri, Brunei; Tony Wass; Monster Music, Madrid; John Richards; Crazy Sound, Guadeloupe; Beethoven Street; Fluke, London; Moles Studio; Spectral Harmony, Bombay; ARC Studio; Haman Studio, Tel Aviv; Kash Productions, Madrid; Zaza Studio, Tel Aviv; Polygram, Hong Kong (Mastering & Studio 1); Loco Studio, Wales; Matrix; London College of Music; Swedish Radio; Polish Broadcast;
Carlton Television (Nottingham & London); Lakeside, Switzerland; York Street Studios; Tape to Tape, London (Heathman's Mastering); Albert's Studio; Telegael, Eire (6 Studios); John G Deacon Founder Conifer Records; Allaire Studios, New York"
also check out:
http://www.audiomusings.com/atc.htm
three reviews of the speakers, just fyi. i tend to agree most with the last reviewer.
and as for pricing, the passive 50's run about 10k, the passive 20's about 5k.
the bad thing about passively amplifying them is that they're no longer active, so you don't have an amp per every driver, which is part of what makes them so dynamic. the good thing is that you are able to choose which amp you would like to use.