Hello, I am considering to buy a submixer to go into my audio interface. I would simply like to have some more inputs for my synths and drum machines and being able to make more use of their individual outs and just in case gain some flexibility.
Then I would like to hook up my delay and my reverb pedal as send fxs.
I do not have any space for a desktop mixer but still an empty rack slot left.
So I stumbled over the Roland M-120 as a candidate that “on the first glance is ticking all the boxes” (watched too much “Bad Gear” on YouTube, I guess). Regarding the age of the Roland … is it still “okay” to use it today? Or are there any cheap alternatives? I bet Behringer has something in their portfolio but honestly I like the charme of an old Roland better.
Mixers that just use up one rack unit seem to be rather rare? And what is a reasonnable price?
Any ideas? Patchbays are not so much my cup of tea I think since I do not intend to change my routing for each project that I won’t finish anyway.
Thanks in advance.
I picked up a Samson SM10 to do this exact thing and it works great.
Rane has some nice 1U line mixers, too, but I agree the M120s have a certain flare to them.
I had one before I had a desktop mixer, and it worked great. The thing to be aware of with any vintage mixer, though, is that their pots might be getting scratchy. And with the 120 in particular, make sure the power matches your country.
I just sold my M-12E which is very similar, and can vouch for the sound quality. Clean and punchy, low noise. I never used the EQ.
I think the Ashly LX-308B Is an excellent modern alternative but you give up effect sends/returns. Radial Key Largo also sounds great if you only have a few things to mix, only one send/return but is in true stereo which is rare.
This is my Samson SM10 set up… I run the Strymon Big Sky (reverb) and Line 6 HX Stomp (mainly for Delays, but other bus FX too).
The SM10 has 8 stereo line input channels, each with an Efx send and a Mon send (which acts as a 2nd fx send).
I have the FX returning individually on channels 7 and 8 (in stereo).
Channels 1-5 are my Sub37, Rev2, Peak, Matriarch and Deepmind 12.
Channel 5 is a Fostex MC102 that I use for recording/sampling in and out of cassette, but this also has its own 10-channel mixer that I can drop more sources into if needed.
It’s great having instant access to FX with any of the synths, and I like how it sonically glues them all together.
The SM10 then feeds into my Allen and Heath Xone 96 mixer where it can all be sent into my computer/DAW, one of my samplers or direct to a 2-track for mixing.
The SM10 is a big part of having this flexibility…and to only take up 1u of space, it’s power belies it’s size.
Highly recommended. 
Beautiful setup!
I agree with Donovan, that is a really great setup! Thank you for sharing and your recommendation. The SM10 for sure is a hot candidate!
Thank you! Two send / returns is a must for me though.
Thank you! There is one in my area so I could check the pots and power cord.
Thanks again guys for all those helpful posts.
For some closure here is what I have actually done now.
Well, none of the above (yet).
I found a Boss MX-10 which I have never heard of before. It is only a half rack unit but gives me 4 stereo and 2 mono channels which should be totally enough (at least for now). Okay, it has only one send / return but I can live with that (also for now). Since the owner has asked for 30 EUR only I simply could not resist without any hesitation.
So basically I have bought some time to save up for a Samson. But 30 bucks vs. 300 bucks for more or less the same functions - just a bit less connections - sounds fine to me. And who knows maybe the 300€ go into the Syntakt instead? 
One final question remains: Now, what am I gonna do with the half empty slot … oh well, that might be a fun conversation in a different thread.