ampeg svt-3 pro

Hello, I am very excited about purchasing my very first bass amp head. Even more excited about the price! I bought it second-hand from a small pawn shop from out of town. The amp is an Ampeg SVT-3 PRO. I knew the price I paid was likely too good to be true. Now that it arrived in shipping...

So I see all of this talk about the svt 3 pro being under powered. Is this coming from people running it at 8 ohms? I run mine through an American made ampeg 610hlf (4ohm) and it slays. I don't have the factory tubes in it anymore, I've upgraded to jj's but still with the factory tubes this...