As long as one source is completely off when the other is on, it might work. However, this is not advisable and you should probably use a switcher if you can. The splitters are using OK to use to for speakers but not for input sources. Give it a shot and see, I guess....

You are not guaranteed to ruin the other piece of equipment, but it certainly is possible.  Here is a quote that may help explain why, from http://silentsky.net/wordpress/archives/624

"Here’s the rule: outputs are low impedance, and must only be connected to high impedance inputs. You should never tie two audio outputs directly together! If you do, each output tries to back-feed into the other, and drive the very low impedance of the other output, forcing both outputs into current-limit. At best, this can cause signal loss, audible distortion (popping and clicking sounds), and weird phasing effects. At worst, over time it can actually cause damage to your equipment."

He goes on to describe what resistor values he chose, for his live-audio equipment DIY combiner cables -- but you can buy inexpensive pre-built switch boxes, either automatic (e.g. www.amazon.com/Automatic-Two-Way-Source-Selector-Activated/dp/B00L9YVL90 but it's touchy to set the trigger volume just right) or manual (e.g. https://soundsheavenly.com/music-input/18-419-aux-input-switch-box-for-multiple-input-devices-to-one-aux-socket-4-way.html#/36-output-5_pin_din_aux ).

Cannot your BS9000 case be done "the B&O way" with a Playmaker?  That's if you are willing to accept Airplay(1) and don't need multi-zone sync of Airplay2, like your Airport Express (if updated) gives you.  See this old thread: /forum/general-discussion-and-questions/multiple-aux-input-to-beosound-9000#post-2064947

Thank, you both for your advices,

The I suppose the wise answer is mostly "no".

Jaffrey2230 wrote:

As long as one source is completely off (…)

One of the devices is an Airport Express, si it is always On and the other a RIAA pre which I suspect will also never be turned off.

trackbeo wrote:

Cannot your BS9000 case be done "the B&O way" with a Playmaker?

I was in a deal to get one of those and started to think it would have been  agreat solution. But the deal wont happen and these things are quite rare here in France and when they pop-up they're also expensive.
But since you talk about that, it would be connect the powerlink out from the Playmaker to the Aux.In of the Beosound right ?

Also thanks for the links. 

matador43 wrote:

But since you talk about that, it would be connect the powerlink out from the Playmaker to the Aux.In of the Beosound right ?

That's how I used my Playmaker (into my BC9500) - you just need to set it to fixed output mode, to avoid having two volume controls.  You can also turn off the Playmakers IR, to avoid other remote conflicts.

matador43 wrote:

But the deal wont happen and these things are quite rare here in France and when they pop-up they're also expensive.

You could consider something like this.

https://www.amazon.com/Automatic-Two-Way-Source-Selector-Activated/dp/B00L9YVL90

It is for always on devices like you have and will be triggered by actually playing something.

Yes, but as Olivier suggest, it is close to a more neat and funnier playmaker.

And to answer to the point about the budget: when, in my wrong mind, it could have been solved with a couple of plugs and some soldering job, it's hard to spend more than a couple of ten's euros now :-D

Will have to wait to find an affordable Playmaker…

Thanks all

OlivierC wrote:

I don’t know your budget, however if you look outside the French border you should be able to get a Playmaker for less than 100 €, including shipping. 🙂

Olivier

Dou you have some links/hints please?

@matador43, my hint would be, "don't bother pricing them in the USA or Canada."  (It's humor, but sadly true.) But in the EU, no problem... @Mikipedia even gave one away during last week's BeoTalk podcast.

@Jaffrey2230, have you actually used that unit?  The high-volume version (auto amp/speaker switch) from the same manufacturer (MCM) is very touchy.  I haven't opened it up, but believe there must be one single capacitor attached (thru whatever different circuitry) to both potentiometers, because a low-volume music piece affects the delay.  For example, it works fine with rock&roll, but an album of classical guitar music will cause the relay to pop over during the silence between tracks, even with the delay set to almost-max and the trigger volume set to min.  In other words, the delay is *not* a digital counter beginning when volume gets to below the threshold, but rather some analog mix-mosh which is affected by the lower (but not threshold) volume of the music which precedes the silence.  Maybe the line-level version is different?