Hey Folksy,
The ES version 1.2 on your 2009 is a very good system, and can sound excellent amplified through a PA such as your 50m. You can use either a graphic EQ, or a DI with a good EQ stack built in. But keep in mind that all acoustic pickup systems --
all of them-- have their own compromises and coloration to the guitar's core voice. All, without exception. The truest way to get your
actual guitar's voice amplified to truly sound like you're hearing it is mic'd properly, and even this is replete with compromises! All to say, curb your expectations a bit when trying to amp your acoustic. But your ES is absolutely capable of sounding great live. I have gigged
lots with the Es 1.2 years ago, and currently gig with the ES1.3 (for many years now), and the acoustic always sounds great through the house.
1. For a GEQ, most anything can help you shape your tone more to your liking. You're looking at around 2k-3k frequency band to smooth-out the upper mids. Slight attenuation in that region will tame that brassiness, and adjust the 4k for your treble, and around 6k for "air" and sparkle. Go easy with any boost in these upper freqs as your guit's tone can get harsh (and fatiguing) really quickly, and it also increases feedback potential depending on your house volume and proximity to the speakers. Small changes go a long way in the overall voice. One of my favorite GEQs is Source Audio's programmable: it has four programmable presets, and offers you
lots of ability to shape your tone. Even if you don't use all four presets, its quality and parameters is worth the price of admission.
2. For a good DI, go with something like a Baggs ParaDI, or better yet a Venue, or Fishman PlatinumPro, or Radial's Tonebone. These are all good units that do not contain any effects (steer clear of such IMO) because the money is in
good preamps and a
quality tone stack. My particular bias is toward the Venue as it has
two sweep bands (the others have one) and two treble bands, all of which give you good tone-shaping potential.
Given what you describe, I'd suggest going the DI route and get a Baggs Venue (or such), and that will go a long way in allowing you to shape your guitar's live tone more to your liking. Hope that gives you a few things to think about
Edward