I would suggest a nice hybrid amp -- one with a tube input stage and a powerful (at least 100 Wpc) MOSFET output stage. With a little luck and maybe a little tube rolling, you should be able to tailor the sound to your taste. Counterpoint, Jolida, Anthem, and other companies make hybrid amps that would be suitable and within your price range. The right interconnects can make a difference too, so don't ignore that area.
An alternative way to go would be to get a nice tube preamp and use it with your present Acurus amp. There are many choices here, and at all price levels.
I'd go for a either a MOSFET/tube hybrid, a 50 wpc Class A SS amp or a strong tube amp. I've run my N804s with a couple of 16 wpc 300B SET amps and a Sugden Au51P power amp, and they just sing. A used push-pull tube amp mated with a passive line stage might be just the ticket.
For hybrids look at the various Blue Circle amplifiers. Currently BC24 and BC28, but also a used BC2 Mono's and the BC6.
Among the various speakers Blue Circle uses to demo their designs, it includes the Nautilus 804.
Are your 804 matrix or N series speakers? B&Ws are not bright speakers. The Halfer amp can be reasonably moded by Musical Concepts and they would sound great. I would say experiment first with the Halfer mod. B&Ws generally come alive with high current SS amps especially if yo uare going to really rock out. Borrow a different preamp to see what that does to your system. Other amps that work well with B&Ws, Bryston 4s, Krell KAV-250 come to mind for loud rock. What cables are you using?
The Aronov Audio LS960i is a no fuss tube integrated which can really give you natural and musical sound, including the bass that transistor fans swear is theirs alone.
Available used in the $1600 range, when it comes up on Audiogon. I mated it with top of the line Mapleshade power cord directly into the AC wall outlet, and for jazz, and rock, the drum kit provides explosive dynamics with great transient speed. Doesn't disappoint when it's just a fragile singer-songwriter with her solo guitar, either.
Thanks very much for eveyone's response. these are the Nautilus 804's, and, I just ordered some Audioquest type 4 cables (bi-wire). I will have to think about interconnects next. From the responses, power seems to be a common answer. Any thoughts on integrates...Musical Fideliyt, Simaudio ?? Thanks again everyone !
naim 250 rocks with the natilus
What about Classe? They seem to mate very well with B&W. Something about synergy with sister companies that you can't get elsewhere. Just something to think about. I think the CAP 151 would have enough power for your 804's.
If low price doesn't scare you away, now that you are considering new interconnects, consider a money back home trial of interconnects from designer-manufacturer email@example.com
When you listen to your favorite music in your own system, you will be very surprised how $120 interconnects bring out the best from your choice of high quality preamp/amp suggestions posted above.
I replaced $995 interconnects, so get ready to hear what the high end is all about.
Musical Fidelity A300 150wpc integrated for ~$1,000 used. Rowland Concentra is also nice but it costs $6,000.
You should definitely try a Tube preamp. I have N804's and it changed by system sound tremendously- really brought out some sweet bass. The mids and highs were always very good. I have an adcom 545II amp and it sounds great, so your Hafleer should be fine. I have a Cary SLP94 Pre, used under $1,000. I'm very happy with its sound!!
I'm using the N804s with a BAT VK-3i. A very, VERY sweet sound ... you won't be sorry.