Noob Amp question.

The stickies have a lot of info about this.

That said you dont have to turn the amp all the way up. In fact your cab rated at 1000w probably cant do anything with anything more than 500 or so watts. If you need to be loud to the point of needing 1,200 watts of power you are going to need more speakers at which point bridging becomes a moot point as you can run two cabs, one off each side of the power section.

 

It's like having 2 power amps in one, like a PA style poweramp. Consider each side it's own independent 600 watt amp. Bridging is like putting the 2 amps together to make a single big 1200 watt amp.

The 600 is enough to drive your cab to full output and beyond, no matter what the wattage rating says. You could play it at the 1200 watt setting too if you're careful. Use your ears, if the speaker gets distorted, turn down. The amp isn't putting out all that power unless you have it turned up to full output. That doesn't necessarily mean 10 on the dial, but you're not using all the power all the time.

 

What's the impedance of your 410? If it's an 8 ohm cabinet that transistor SVT will output +/- 300 watts a side, not 600.
With a cab rated to 1000watts, I think I would run strapped regardless of the cab's impedance.
With an additional cab I'd go dual mono.

 

What cab are you using that you have switchable impedance?

 

Unless you are playing a cab specially built with speakers that have dual voice coils, your cab is one or the other - NOT both.

 

Is there anything written on the jack plate?

 

The website is saying that you can order it either way. Presumably if your manual says 8 ohm then that is what you have.

 

Go to low and it will fry your head, as it will draw more current than its designed for. An 8 ohm cab will receive less power than a 4 Ohm cab if all the other physical specs are similar, but you wont actually hear the difference. That said two 8 Ohm cabs will be about 6 dB louder than just one of those same 8 Ohm cabs with a SS head.

 

According to the Ampeg spec sheet for the SVT 4 Pro the amp outputs about half the power at 8 ohms than it does at 4 ohms in dual mono, so if you run one side of the amp you will experience a -3 dB difference with an 8 ohm cab vs. a 4 ohm cab.
I think most people can hear that.

You should get a multimeter, then you'll know for sure what your cab is. They come in handy for a lot of things, every gigging player should probably have one, especially those that gig tube amps.
You can get one for $5, it's certainly worth the money IMO.