Subwoofer upgrade advice - bk xxls400 or monolith


Established Member
Hi all

I have monitor audio bx speakers , a Yamaha 671 receiver and a bk xls200 subwoofer in a small room 3m by 3m. I am looking to upgrade my subwoofer to either the xxls400 or the monolith to be used mainly for movies.

I really like my xls200 but I cant help but feel like I am missing out on the really low frequencies and that I am not getting enough oomph.

I am really struggling to decide between the 400 and the monolith , I think that the 400 might work better in my room because it should be easier to place but with such a small price difference maybe I should opt for the monolith.

I am also using a anti mode to eq the subwoofer.

Would the xxls400 perform just as good as the monolith in a small room ? or would I be best spending that bit extra for the mono ?


Established Member
If you are using it for movies then the monolith is what I would get I was like you last year and the price is so close but.... and is what you might or might not know is P+p on the monolith is £30.

Its big there is no other word for it when you get it except OMG but its one of the best things I have got for a long time that for the price you smile when it lets you know how good it is.

That and if you are like me you will always think what if I had got the monolith, I never think what if I had got the 400.

Find space when it turns up. what finish you going for ?



Distinguished Member
Many thanks for the reply , will go with light oak to match my other speakers.

You won't regret it; especially if you get the Mono DF, it becomes a piece of furniture for a table lamp, photos, stuff, really well worth it
Never had a murmur from my wife when it arrived and she had nothing but praise for the walnut veneer finish.


Established Member
I have a BK200xls and went through the same thoughts.

I eventually ordered the Mono DF+ - I'm sure it was the correct choice.

I did have to reposition a chair into the spare room though.:)




Established Member
Many thanks for the replies

the only thing thats stopping me from ordering is that I listen at a low/modest volume level , usually around -25db and I was wondering if I would get the benefit from owning the Monolith

How does the monolith perform at a lower volume ? do you still get some impact from explosions etc


Standard Member
Hey Crossfire, I got the Yamaha rx-v671 with a DF Mono, you'll get loads of smiles with that amp and a mono at -25db, I use mine at -35 for TV and -15 when I crank out the tunes.

I've never spent a single moment wondering if I got the right sub, I'm well chuffed with it :smashin:


Established Member
-25 you will be fine..

Movies for me are -16 -10 Tv is -25 ish

stop thinking about it and click the botton. once you have it you will not stop smiling.

All you need to do is find a good film with lots of action and some good sub work out parts.

That and its like waiting for a sofa so dont expect it next day :-(

You can return it if you dont like it but I am sure you wont be doing that


Established Member
Thanks for all the help , its much appreciated.

Gonna order a monolith FF light oak , really looking forward to when its built.

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