invite a friend over to sing and play their acoustic guitar for a while and record it.
ask your friend to play the same music on the guitar while you listen to the recording on your 'rig'
life headphones on and off, if things dont sound very close you need to change something.
I agree with rhythmdevils, neutral is not analytical, however I don't believe the op wants a truly neutral system, I think he just wants something that can reproduce good quality sound, go and listen to something truly high end, "reference quality" if you will, and see how you like it
as far as the comment about genelec, mackie, and dynaudio in recording studios, yes, they are found in some recording studios, you'll also find Yamaha, JBL (at a price range high enough to give most people a nose bleed), Bowers & Wilkins, and many, many others, engineers and studio designers have their own interests and tastes, and they don't always buy "studio monitors", so don't be so fast to talk rot about "audiophile rubbish" (which is a pretty ignorant generalization, audiophile grade speakers exceed $30,000 a piece, and we're not even talking about $5000 for the complete system here)