Most, if not all, decent "acoustic guitar" amps have processing (usually digital) to sweeten the sound- and it is almost always artificial. This is not to say it sounds bad- they usually sound quite good (even Behringer's ACX line.) I recently traded, straight across,
a Behringer ACX-1000 for a Fender Super Chorus. The guy just could not get a decent "acoustic" tone through that amp. The truth is piezo pickups just sound like crap, by themselves, and you can not make a silk purse out of a sow's ear. Their best feature is they are very unlikely to feed back- but think about it- acoustic guitar feedback happens because the acoustic guitar body that does such a good job of acoustically amplifying the sound, also does as "good" a job of amplifying the electronic feedback. I am expressing this poorly, but my point is, if you want the best acoustic guitar sound, you gotta use what gives you the best acoustic guitar sound- that being the body of a good acoustic guitar. Bypass that- and a piezo picks up the sound directly from the bridge, not from the body's resonation- and you lose that nice acoustic sound. There are all
kinds of things happening inside and outside an acoustic guitar's body- natural reverb, delay, resonation, sympathetic vibration, etc. etc- that the piezo NEVER sees. A good acoustic guitar amp simulates much of that- plenty enough to sound good in a live setting- but recording is a different world, and you will get better sounding results by recording through a mic. Exceptions like tonesponges Taylor do not disprove this- maple is, perhaps, a poor tone wood, and even masters of the art like Taylor and Martin make mistakes. Nobody fully understands
everything that's going on with an acoustic guitar, nor does anybody fully understand the whys and hows of what parts they do understand. I am going to make a bold statement, and I make it without fear of contradiction:
A well-made acoustic guitar is such a complicated thing, what with the millions of variances in woods, the ways they are processed (even cutting a tree down is a process...) and post-production factors like aging, humidity of the wood and air, etc. etc. an ifinitum, that NO one, even if they truly had God (if there is a God) on their side, will ever duplicate the sound of even ONE well-made acoustic guitar. Close, maybe- but close only counts in horse shoes and nuclear strikes.
Mic your Ovation. That's your best bet, but if it does not sound good then, it's just not a great recording guitar. It may well be a good guitar, or a good live guitar, but being good at one things does not make a person or object necessarily great at another.
Oh, and I truly hope I didn't offend when I said your Ovation probably was not worth as much as you thought or hoped. Dollar value does not, in and of it's self, make a good guitar.