Is the Bass Block V803 safe on a 2-ohm load?

It's safe. Our amps are protected against load faults and opens, so a 2-ohm load won't put the unit at risk. That said, 2 ohms pushes the amp beyond its normal rating, so on loud peaks it's possible (though rare) to hit overcurrent limiting, which shows up as harsh clipping. In practice we haven't really heard complaints about it. Here's the mechanism worth understanding: speaker impedance tends to rise as you push the power hard enough to reach that limit, and normally the amp gently backs off power when it's driven too hard for too long. If peak clipping does creep in anyway, just lower the Master by degrees until it clears, which keeps the peak currents in a comfortable range.