Have you tried switching the 2i4 direct monitor to mono?

Assuming you are using the headphone output of the Focusrite with the monitor control turned fully to monitor the input, it means that you have a L and R headphone signal feeding the L and R inputs of the SP404. Since you are only using a mono mic feeding one input of the pre-amp, it stands to reason that you are getting only a one-sided result.

Your photo isn't very clear, but I can see croc clips and other means of connecting the two units. What you need is cabling to pick off just one of the headphone signals and send that to both the L and R inputs of the SP404. There is no standard cable to do that job, so, short of soldering up your own, this calls for a standard cable plus appropriate adaptor cable. The standard cable is an insert cable (using only one half), then use something like a mono jack splitter cable to feed both of the SP404 inputs. Look for the Keen Eye instrument cable splitter from Amazon. Sorry I can't paste links when I'm replying on my phone.

I think he's using the dual 1/4" main output on the back of the 2i4, with a paired 1/4"-RCA cable going to the RCA inputs of the sampler. There's a good chance just switching the input monitoring to mono will put the signal in left and right of the 2i4 output.

That was my original thought as well, but the problem with using the main outputs is that they are balanced as well as +4 level, both of which are incompatible with the unbalanced -10dBV inputs of the SP404. At least headphone outputs are unbalanced, and there is probably sufficient gain reduction with the volume knob.

The mono switch is a good idea, and might save the cabling fandangle, but the other two issues are still there.

Doesn't the 2i4 duplicate the 1/4" output on a pair of RCA connectors?

I'm on my travels at the moment, but have just got to a place where I can download the 2i4 manual, and you are correct about the RCA outputs. I was mis-remembering and confusing the 2i4 with another unit. What I don't know is whether the headphone level control affects the monitor level at line outs 1-2 as well as the headphones.

However, assuming that the SP404 has an input gain control, it looks as though simple RCA-RCA leads will work along with the mono button on the front of the 2i4.

Boswell, post: 455776, member: 29034 wrote: What I don't know is whether the headphone level control affects the monitor level at line outs 1-2 as well as the headphones.

It does sort of hinge on that. If not, an adapter would be the solution.

Thanks for the responses. I haven't been able to try the solutions yet. But ill report back when I do. Cheers