Even though I don't have a 3K amp and don't ever expect to have one, I say yes I can justify it. Can an amp be worth $3000? Of course!! If an individual deems it to be, for them it is then worth it. Would I personally go $3K in debt for an amp? No, my enjoyment of the amp would be offset by the pressure of the debt!
But it is relative to both your financial means and how important it is to you personally to own a given amp. For instance, I personally won't (at this point anyway) spend $30K or $40K on a vehicle, but I know tons of people who do it. It just is not that important to me, although I could finance one if I chose to. But if I got Jonesin' for an $3k amp bad enough, for me that would add more pleasure and enjoyment to my life that owning a $30K-$40K vehicle. It's all about what resources you have and how you choose to allocate them.
Or compare it to spending $3K on a vacation, I've done it, lot's of people do it. Is it worth it? You have to ask the individuals! With a vacation, the value you have is experiences and memories. On the other hand, with an amp you've got something tangible to enjoy on and on. So... I should've just said YES and left it at that!