Doesn't it have XLR outs? Try those. Better quality too.

What speakers or monitors are on the other end? Many things can make a difference.

Did you try plugging your headphones into the UMC and/or bypassing it like using a mixer. Does the UMC suck or is broken, it's only $80? Just haven't used one before.

I have a UMC too (404HD). I only use it as a reference - I don't really care much about maintaining pristine quality. That said, I can think about use of the gear and maybe help get the best out of it.

I was thinking the same as David - when you use headphones does it sound great when using the headphones plugged straight into the YC88's PHONES jack? Does it sound just as good when plugged into the UMC's headphone/monitor jack? This would bypass some of the stages and let you know if you need to focus on the input side of the UMC.

Assuming the headphone sound you're saying is good and airy is from the YC88's headphone jack:

On the input, there's the cables. "Mono cables" doesn't say unbalanced 1/4" or XLR. They're both mono. But if you're using unbalanced 1/4" then perhaps some noise immunity can be gained with XLR. Really shorter cables can get you there too if you have really long cables. I don't expect a big change - but here in the studio I have two different cables (both 1/4 inch) for one keyboard and each is different judging by the adjustments I have to make at the inputs (gain). So there is something to be "gained", perhaps by cables.

Then there's your leveling. On both sides. Since this is an analog connection - you need to get a sweet spot of the YC88's level going out and also dial in the gain of the corresponding inputs on the UMC side. On the UMC side - I generally just use the "peak meters" (single red LED) and play a "loud patch" with a lot of velocity. If I peak the channel, I'll roll off the gain a bit. Rolling off at the UMC vs. the YC88 is a matter of experimentation. You may want to set the UMC at 12 o'clock and roll back the YC88 - but that may not be the best.

On the UMC side there's also Line/Instrument switches for each channel. Although each has a specific purpose (an expected level coming in) - you may find that one setting sounds better over the other. So feel free to break the rules here and go by ear.

Then there's a pad switch. Make sure that switch isn't activated. It's meant for really hot sources and squelches the channel considerably to deal with those. You shouldn't need to use pad.

Then last, there's the phones level on UMC. By last - I mean when adjusting the input side of the UMC. There's an output side too. But the goal here is to make sure the headphones plugged into the UMC have a nearly identical sound as what you hear when you like the YC88's sound. If you can't get this far - then it's possible the input side of the UMC doesn't cut it. The UMC is a fairly budget box. I like the flexibility it has for the cost. No need for a computer - so acts as a monitor mixer for multiple keyboards. The soundcard interface is a bonus and I mostly use this to mix in my computer's output to the studio speakers.

Thanks for your response! The UMC doesn't actually have XLR inputs, so 1/4 inch it is. The $80 UMC is the one that has like two inputs, I think the one I got was around $2-300? It's been serving me well. I'm just listening straight back through the headphone out on the UMC, no speakers or monitors involved.

Just now I did an A/B recording with the YC audio interface vs. the UMC inputs...there was a stereo/mono button that I may not have toggled correctly on the UMC....:p

Listening to them back to back, there definitely is a much smaller gap between them now, but it's still noticeable to me.

https://drive.google.com/file/d/1t2jV_lDwVOtT4mIi-4NlYgSuVMN8Tp1r/view?usp=sharing

The 404HD has 4 XLR inputs - I still use the 1/4" since that's what the stage gives me at shows. They drop me a mono DI. My 88 is going stereo - but that's still 1/4". It's fine for short runs without interference assuming the cable is reasonably well made.

Oh snap, sorry Jason, when I was responding, I hadn't seen your post yet! A lot of good info in there, I'll get back to you when I try all that out.

when you use headphones does it sound great when using the headphones plugged straight into the YC88's PHONES jack?

Yes.

Does it sound just as good when plugged into the UMC's headphone/monitor jack?

No.

On the input, there's the cables. "Mono cables" doesn't say unbalanced 1/4" or XLR. They're both mono. But if you're using unbalanced 1/4" then perhaps some noise immunity can be gained with XLR.

Whoops, you're totally right, the UMC--1820 by the way--does have XLR inputs, I just always assumed they look like the "three holes" only.

Then there's a pad switch. Make sure that switch isn't activated. It's meant for really hot sources and squelches the channel considerably to deal with those. You shouldn't need to use pad.

*turns off pad switches while nonchalantly whistling*

Then last, there's the phones level on UMC. By last - I mean when adjusting the input side of the UMC. There's an output side too.

Are you talking about the Monitoring section?

Monitoring is the level to the outputs. I thought that would be independent from the phones knobs. Maybe not.

I was referring to the "PHONES A / PHONES B" knobs. Whichever one you're plugged into.

Also be sure to turn off the phantom power switch. You don't need that. It's going to matter (turning it off) if you start using XLR since phantom would be delivered on XLR. This is one reason why just sticking to 1/4" is "safer" (easier) - you don't have to worry about injecting phantom power into a device that doesn't need it. For now phantom power doesn't apply since using 1/4". I would still get in the habit of turning off phantom power. The UMC1820 allows for turning phantom power on/off in banks. Inputs 1-4 and/or 5-8 can have phantom power turned on. If you have mics that require phantom - I would turn phantom on for only half of the inputs (choose 1-4 or 5-8 side) for the mics and then plug the keyboard into the other side where phantom power is turned off.

The inputs on the UMC1820 are combo XLR/TRS. Meaning they take in balanced or unbalanced 1/4" OR XLR on each input. This is a common configuration to conserve space to mount the connectors.