Welcome to the forums, John.
It's a good question. You can't swing a dead cat on this forum without finding people with significant real world experience. We have a lot of people here with a lot of expertise.
It wouldn't surprise me if there is a fair amount of disagreement on this issue. That's fine. I'll give you my view.
Sound cards have their place. The absolute best way to output sound from a PC is digitally, either by USB or HDMI, or some other more exotic interface. The analog output stage of most sound cards is, to put it gently, garbage. But the Soundblaster AE5 is a good sound card, especially by the standards of sound cards. If you really wanted to use the analog output stage on a sound card, that would be a good one to pick.
You don't say why you might want to connect your sound card to your power amps. If budget is an issue, and you want multichannel, get a receiver. If you only need stereo, you can get a Topping DAC for the same money as the Soundblaster. If you need multichannel and prefer a separate DAC, the Okto DAC8 Pro is a great choice.
I like Yamaha. That particular product is not their best. If you are using separate power amps, why are you looking at a receiver? A processor or pre-amp would be the more appropriate choice. Yamaha makes the CX-A5200, which is very nice. Yamaha, Marantz, and others make nice processors that don't have built-in amps. I prefer Yamaha to Marantz. They sound more musical, and run cooler.
I would never, under any circumstances, even as a bet, hook up a sound card directly to a power amplifier.
It's not about output voltage, or signal to noise ratio, or noise filtering, or distortion, or any of those things. And it's not even about user error or other misconfiguration. The reason is much more unavoidable:
PCs sometimes crash. Especially PCs with SoundBlaster cards in them. SoundBlaster drivers sometimes crash all on their own. And when these things happen, sometimes the result is not silence. Sometimes the result is hum, random digital noise, or a constant repeat of the last samples that were in the output buffer. There have been SB drivers that output a hum whenever the driver wasn't initialized (meaning, as soon as you powered on the PC but before the driver loaded, or after you shut down the OS but before power was cut).
And that noise can be output at full line level, without attenuation.
Result, when connected directly to your power amplifier = Blown Drivers.
Just for that reason, hooking up a PC directly to a power amp is the height of recklessness. It's just madness.
Lots of people probably do this with low power headphone amps, that don't have the power to damage their headphones. Fine. But you said power amps.
Now your speakers may well survive if the amp you are using is a small affair with the power of a harnessed fieldmouse, but if you're talking hundreds of watts per channel, then it's simply too dangerous. Don't do it. I'm sure there will be people who will say "Oh I've been doing this forever; never had a problem." Good for them. It's like leaving a loaded gun where you kid can get to it. Luck.
That's my advice.
Good luck...