Yes, a 350 watt head into a 300 watt speaker will work if you play with care and understand how easily you can destroy speakers.
In most cases, speakers are damaged due to abuse and and not excessive power ratings as long as the speaker holds together as designed.
Uncontrolled peaks/spikes in the power flowing into the speaker will cause violent movement of the cone that can tear the suspension, fold the cone, or burnout the voice coil from excessive excursion.
I certainly would not turn up a head with a greater watt rating to 10 just to test the speaker.
You can also destroy a 400 watt speaker with a 100 watt amp.
For example: I am powering a 400 watt 15" with a 100 watt amp. If I max the gain, master, and all of the frequencies, I would have a violent, clipping tone that would ruin my brand new speaker in a short time. Is the lack of control within the magnetic motor of the speaker that causes overpowered distortion to rip the speaker apart.
It's not unlike trying to get a car out of a snowbank by quickly jamming it in forward and reverse and flooring the gas in each direction with out even pressing the brake.
Your speaker is built to drive fast but everything needs control or you will lose it.
As you increase the master volume, if the distortion is coming from the speaker when the amp should be a clean tone, then you know you have that bad kind of distortion. Just back off any excessive frequencies and reduce the input gain and bass slightly to see if it clears up.
Anybody have this paring?
Neo 1x12 and MB2-500
If so can you provide details of its wattage handling and tonal possibilities?