I would think so...however, I'd also be concerned that there was a potential mismatch if the idea is to plug the modular right into the amp. While the A-138d is designed to be used with stompbox send/returns, plugging it directly into an instrument-level input might cause both some overloading and impedence mismatching. For that reason, you might want to look at a load-matching device such as Radial's Tonebone Dragster to correct any issues in that connection.
And admittedly, I'm not 100% sold on using the A-138d for that purpose anyway. It's not bad as a send/return, but I think there's better and, more importantly, smaller candidates for that out there (Malekko, Bastl, etc). As far as outputs go, though, get something that has some isolation on it (ground loop hum issues between synth and amp are a very real possibility!). But looking a little further, I do see something of a problem with using the Ears module as an input. For one thing, it has no direct input jack for a 1/4" plug. It's also intended as something of a contact mic module...not exactly what's called for here. My suggestion would be to look at Sputnik's EF/Preamp instead; this offers impedence matching for instruments, has a full-on envelope follower, decade-switched input preamp level control, and the proper sort of jack to hook in directly to the modular.