Which Amp for new B&W 804 Diamonds

I would also throw Plinius, Musical Fideliity and McIntosh into the mix.

B&W and Classe is an obvious starting point - however in regards to their being a ceiling for amplification I dont think there is - I asked this same question to Ket from WHF and his answer was clear - no it just keep on getting better the higher you go.

The recent review of the 802D loved Krell amplification so that is definately another company to consider - I think with B&W the more proper power the merrier - my old N805 wanted much more power than I could feed them at the time, they would have sounded special with the right gear and conditions, gutted didnt hear it before I sold them

By the room I did mean dimensions/ speaker placement which you have right by the sounds of the triangle etc but also some consideration for your rooms acoustics.  You are planning on spending another potential £5k on amplification after already spending £4ish on speakers plus the rest you have spent - that well over £10k's worth of equipment.

With all this top gear - you want to hear the gear and not the room - maybe look at some of your budget going into some room treatment to get the very best from it

That's interesting. I wonder if they played any modern electronic music and tested bass control?

That to me looks like the perfect example of hearing the room not the kit.

Those speakers need much more room than that and they are right next to a window ..... Not good.

i wonder if there is any treatment in the room at all - makes £200 gear sound like £12000 in the same environment 

Absolutely, and that's the main stay of my music collection. I have a serious issue at the moment with the Purity Ring album "Shrines", I can't stop playing it! Electronica through a system is the real test for me

Don't know.  The result didn't suprise me too much, the amps were level matched and tested to make sure neither was clipping, under those conditions most amps sound the same when blind tested.

If I was in the op's position I'd base my decision on 2 things - does it have a good amount of dynamic headroom, does it look nice.  Actually, there'd be a third consideration - are the Rotels in good nick, because if they were I'd probably just keep them.

I've dreamed of having 804s or 803s (really I'd like 801s but that will never happen), and my existing amplification is Cyrus Mono X300s.

No-one's mentioned these as an option - is there a big incompatibility problem of Cyrus with 800 series, as they go really well with my B&W CM8s?

(I like the studio monitor sound, by the way, as this is what musicians hear when they sign off the record as being "good to go")