The second one is much more pleasant to the ears since it's in stereo.
I'm particularly 'allergic' to mono sound. We've come so far technology wise since 1920's when mono was the only way to record.
There's a lot of 'colour' that you're losing in capturing in mono. Yes, you have to deal with significantly bigger file as a result of stereo recoring, but the sound benefit is well worth it.
And I'm glad you figured a way out how to have your speakers on, and capture in stereo at the same time. Although using splitters may not be the best option if you're after the best possible results, but if that works for you and you're happy with it, I guess that's fine.
BTW, Happy new 2019!
Take care.
Valentin