I've got a couple of 3124's but you are trading two preamps for 4. I'd gladly send you 2 API 312 cards since I have 4 of those sitting around. Of course they're not ready to just plug in and use. You'd need to mount them (figuratively speaking) and add a ± 15 volt bipolar power supply, a couple of gain pots, LED meter & 4 XLR's. Heck I might even consider sending you three 312's?
How about 4 Op-Amp Labs BM 360's already mounted with a power supply and ready to go? Same size as a 3124 but not including any phantom power. No?
I'm a dealbreaker. LOL.
Mx. Remy Ann David