I don't know if they still sell the Groove Tubes GT-33 for cheap or not. But if so, I like that one a lot on accoustic. A lot. Oktava MC-012 is nice, too. I know this one gets old, but it depends so much on the context; whether the guitar is the featured / focal instrument or if it's in a busy mix ... whether it's being picked or strummed ... fingers or pick, etc. So many variables.
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