golemto

I just bought a HD 300 recently from Ebay and it was a demo model as the seller said that. Currently i'm using another HD 300 that i borrowed from my friend. The problem is that there is a huge difference in sound between these 2, as the new one sounds like lollipop even though i set 2 units with the same setting. It seems like the new 300 sounds without cabs or loose a lot gain. Anybody has experienced this before or know how to solve this please help me ~.~