Atari ST with SC55 how to mix the sounds back in?

[Brettster]

I've been playing with the Atari ST core and have a working setup using a Roland UM-ONE and an SC55, sounds great but whats the best way to mix the sounds from the Roland back into the MiSTer and have all the audio come out together over HDMI?

I've been looking at the ADC adapter that says it supports stereo input but at not very good quality.

are there other options for a quality line in and is this actually supported by the cores?

would like to use this for the ST, Amiga, X68000 and the PC cores too if it works

[zomgugoff]

I have a similar situation. I have solved it using optical audio from the I/O board and my gaming PC's line-in ports to mix the audio to my wireless headset. Essentially, you're going to need a mixer. Assuming you have an I/O board with the 3.5MM/optical audio port, you could run a cable from it and the SC-88 to the mixer, and output to a sound system/TV input (assuming it has inputs).

If you're trying to mix your SC-88's audio into the existing HDMI signal, there are mixers that can do that, but they're very expensive.

[softtest9]

There might be home theater receivers that support outputting audio from two sources at once (and many receivers have HDMI In as well as RCA Ins), but I'm not knowledgeable about them and they're expensive.

If you got a set of speakers connected to your TV now, I would suggest just getting analog audio from the TV into your SC-55's RCA Ins, and then connecting the SC-55 to your speakers. Or, if your speakers have an AUX In, you could connect the SC-55 to the AUX In instead and let the speakers mix the audio.

If the quality is inadequate, another option would be to use a sound card, and connect both the TV's audio (through SPDIF if possible) and the SC-55's audio to the sound card. The sound card, or your operating system, would do the mixing then.

[Brettster]

Ah thanks for the Ideas.
does the line in or ADC port need to be supported in a core or does it always pump sound into whatever you are running?

Otherwise I may just stick to running these via CRT and mix the audio via the SC55

[Televicious]

Audio in is for datasette in a few specific cores. They say it isn't high enough a sampling rate for actual audio use. I always just ran mist/mister sound through my sc-88 or if using mt-100 had an audio splicer connected.

[Mellified]

I have an MT-32, SC-55, and mt32-pi connected in series to my MiSTer. I am using this mixer:
https://www.amazon.com/gp/product/B0721SBHVD/
Input 1 - Reserved for bluetooth from my phone
Input 2 - MiSTer
Input 3 - old MT-32
Input 4 - mt32-pi
Input 5 - SC-55v1

I also use this:
https://www.amazon.com/gp/product/B07F6QXP7N/
This allows me to extract audio from the MiSTer's HDMI output, send it to the mixer, then take the mixed audio and inject it back onto the HDMI cable. I quite like this setup because I can adjust the mix between any of these devices. I can also quickly and easily compare my real sound modules with the mt32-pi running in cm-32l mode to my older, real sound modules.