Trust me, the Noisefloor on the Rytm MK1 is very prominent. At least it was on my unit. Check out my Rytm only Videos and you will hear what i mean! Its not acceptable to be honest. I can plug my Headphones into the Korg ARP Odyssey and the Minibrute 2s and i hear almost no BG Noise at all. Being analog doesnt mean that it has to have noise! A totally untrue assumption from a lot of people!
[edit] in regard to my soundcraft mixer: Yes, the input gain helps for sure and it solves this problem. Because that Mixer has so much headroom and its Preamps are of superior quality - you just cant do it wrong but one doesnt always want to use a mixer, or doesnt have one around. And i can totally understand the OPs worries about the Output Level because it was the same on my Rytm MK1 Doesnt matter if you record with OB or with the regular Main Outs btw. The output Level is too quiet and if you gain it up with the Makeup-Trick while the compressor is not working or with the Overdrive you add so much Noise that its just not practicable for reaching the Loudness necessary in contemporary electronic Music! The only way to fight this is to max the actual “circuits” inside the Rytm. Cranking up the Engine to max, cranking up the Amp to Max and the Track level itself. This lead to roughly a -15 db Signal inside the DAW which is the “base” Level an audio Signal should be at - if you want a proper Recording that you can still boost further without adding too much Noise in that process.
I dont have these issues with the Analog Four btw. Obviously i also dont have these Problems with the Digitakt or the Octatrack. They are litereally noise free as well because they are (mostly) digital. I think that Elektron messed things up with the Rytms Output Level. Its very interesting to hear that this also applies to the MK2