Belles original 150 amplifier. Any good?

Hello all, just a quick question. I just grabbed an original Belles 150 amplifier for $50. I opened it up before I powered it up. The caps, etc look ok so I plugged her in and it seems to work fine. 
I’ve read this amp can be sensitive to certain preamps. Any truth to this? Is this amp worth keeping?
any recommendations on a preamp that matches up well?
thank is advance!