Stereo to mono - split cable or the t.mix Volume 1

I want to use two different line sources for my PA speaker (JBL EON 710) one for the left channel, one for the right channel.
Reason: I don’t want to use my audio interface (Motu M4) for a quick play, but use my boss katana go instead, as this is just plug in and no hassle. But for the Motu M4 I need to have my notebook connected and software running.

So my idea is to connect the M4 to the left chanel of the JBL and the Boss Katana Go to the right channel.

As both have stereo outputs, I need to “convert” to mono for the individual inputs on the JBL.

My first thought was to just use a split cable, but this seems to be a bad idea. Is it?
The alternative is two “t.mix Volume 1”, one for each channel.

Do I need that?

Why? It should be able to Direct Monitor just fine with no PC connected.

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You are clever!

Yes, this is possible, but:

  • I cannot use any effects then - like I could with the Boss Katana Go
  • Lesser reason: I still need to power the M4 via USB. That means either connecting to the notebook or to a power supply. I know it’s just small things, but it’s not “plug in the bass and play”!

I use this

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That’s the Lehle Little Dual II, right?

Does it solve my issues?

  • Can I convert two stereo sources to two mono sources?
  • Can I connect a bass either to my M4 or the Boss Katana Go and play to my JBL?
  • Can I connect the Boss Katana Go to the Lehle and output to my JBL?

Also: two T.Mixes kost 70€ (35€ each) - the Lehle costs 220€. What would be the advantage that justifies the price difference?

EDIT Important: I send a mix of playlong song and bass to the JBL, either via the M4 or the Katana. That means, that stereo/mono conversion must happen AFTER the M4 or Katana - not after the bass…

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There are quite a bit of ways to connect this pedal, check it out.

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For my use case, I would need two of them, right?
Cause: “for dual-mono or stereo operations”.

Too expensive!

So, a normal splitting cable would not work? I don’t need all the fancy stuff. No muting, no reconfiguring, even no volume adjustment. Just stereo to mono…

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I guess it depends on the cable. I saw the guy using the splitter I thought it was cool idea so I got one. His is a DIY and while it looks simple enough for an average player, it’s just a bit outside my understanding, :joy:

There are a bunch of ABY style pedal switcher for about $30 on amazon. Doner makes one too.

Lehle transformers are sooooo much better than any cheap ABY switcher. I even considered one for my pedalboard to clean up white noise and improve my signal. IIRC some Lehle units can also run without power.

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Yeah I saw the video with the owner talking about the trigger and how they are different than others I thought wow, I gotta see how it is. It feels as good as it looks and perform even better.

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That is cause of the galvanic isolation, right?

I shortly looked into that when I had issues with hum on my passive bass.
But after rewiring everything, removing some devices from the same power socket and do some other magic, everything is free from humming, krackling and hiss now.

Yep, they even have a unit specifically made just for isolation, like this one LEHLE P-ISO TRS XLR | Isolator | Products | LEHLE

So to justify the price, a Lehle ABY switcher brings extra features:
Hum and noise-free switching
High-impedance transformer with phase and ground switch
Stereo-routing option
Active pop suppression circuit

I would still say it’s a luxury unit, especially handy if you have complex signal routing involving multiple amps and instruments. Lehle is like the German version of Radial, just a bit more aesthetically pleasing to look at IMO.


Just pan all stereo signals on the inputs fully left or right and use that cable as a mono cable. This is actually fairly standard, and a lot of stereo inputs have adopted the convention of using the left channel for mono inputs as well.


If you have a problem with the signals using the splitter there’s a special splitter cables I used on my Roland V-Drum when the regular 1/4” splitter doesn’t work.

Then again if you reach that point it’s cheaper to buy a $30 ABY switcher.

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It’s not that I have a problem with a spiltter. I read somewhere that merging the two stereo signals to one mono signal has some side effects, if you “just” use a splitter…

Got a pair of Thomann T.Mix Volume 1 now. It’s perfect! And only 35€ per device…

I have now one channel for the Motu M4 going to my JBL EON 710 and one channel for the Boss Katana Go for a bass quickie!

Audio quality is great, no volume loss. A cheap and good solution!