S400 bi-amp conversation

I’ve obtained another pair of monoblocks which I would like to use without changing my S400s. Is there any way of modifying the crossovers to accept another input? I’m sure I read somewhere that there was.

The S400s can be made active if that’s what you mean. You will need an appropriate SNAXO (BMR type) and power supply for the S400s.

More about active operation can be read here:

Hi Richard thanks, I read about this in the manual. The active lead bypasses the crossovers which allows you to connect your own active crossovers. I want to use the passive crossovers but modify them by separating the 3 circuits. I haven’t looked yet but it should be possible.

That would entail discussing unofficial modifications which falls outside of the AUP of this forum.

Hey Richard,
My understanding was that the S400s have a higher crossover frequency than the S600 & S800 model. So I thought the BMR crossover wouldn’t work with the S400s.
Have things changed?

Why would you want to use speakers not designed for biamping in this way? You’d need to modify the crossover and results would be unpredictable. It’s better to get a bigger single amplifier rather than using two smaller ones in a biamp arrangement.

It needed a slightly different BMR crossover. But now you mention it, I’m not sure whether it ever appeared. IIRC it was due to appear sometime in 2011 but I don’t know whether any were made (it was after my time at the factory).

Oh sorry. Thats probably why Naim didn’t reply. I respect their view on bi-wiring but I like to play, isn’t that half the fun? I’ve been happy with the S400s for the last 12 years but was disappointed to find them without the option.

As far as I know it’s never been possible to run the S400 active.

Thanks HH. It was definitely planned though, but i couldn’t recall whether it ever made it to release.

My ProAcs have biwire terminals, meaning they could be biamped, but I’d really rather they didn’t. I asked ProAc if they could supply a single wired version but with the crossover design it’s just not possible. The crossover is such a key part of a speaker that modifying it for a different use case would seem very hot and miss unless you were in possession of the necessary test equipment.


Naim did the right thing not supplying any biwire terminals on their speakers ever.

These would always provide reduced performance, better to avoid if at all possible.

I’m surprised some people are disappointed finding biwire/biamp plugs are not present, it should certainly be the other way round.

Yes, the manual said the crossover for the S400s was in development…
I bought mine in late 2013. Then I read they dropped the idea.
I think they do some customisation of the regular SNAXO cross overs for the Kudos range, so your comment got me thinking… whistfully.
I know a NAP 300 would probably do a better job than 3 x 250s. But I have a sentimental attachment to the concept of all those green lights.
I am about to get a NDX, and as soon as I can find a 252 and 300 the S400s will have what they have always needed…
But those green lights keep calling me.

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