Unplugging amp while it is still on, damage?

Probably not. The only thing that might be hurt is you speakers. If you play them and they sound fine they should be.

Turn it on. See if there`s any sound. Start @ low level. If no sound, then check fuses. Always power down when shifting & pluging equipt.

Power goes out all of the time at my home and I've yet to have a problem. That's effectively the same as unplugging it. I suppose something could happen, but I doubt it did unless there's something very unique about your amp. Loud thumps are pretty typical too. Chances are in fact that pulling the plug has exactly the same electrical effect as turning off the power switch . . . again, depending on your amp.

I would fire it up and see if it works.

I just hope your speakers are OK ? If they are and assuming your amp is not plugged in, first, turn your amp off with the amp's power button if you can while the amp is unplugged. 2. turn your preamp on and put the volume at low setting, say around the 8 o'clock setting. 3. turn your tuner on a station or get your CD player playing with a CD in it. 4. plug your amp back in the wall and turn it on. This is the way I would do it. Don't forget with lightening storms we all lose power sometimes and the equipment gets turned off because of a storm. In this situation I always unplug everything until the storm is over.

I should have specified that this is a integrated amp, a portal Panache to be exact. This amp does make a loud thump when turned on, which is normal. I guess unplugging it while on and plugging back in would be essentially the same as turning it on? The speakers work and the amp seems fine...

Seems like you are good to go!

Some of the Sunfire Signature amps did not have an on-off switch. The only way to turn the amp on and off was to plug it in and unplug it.

In the future if you accidently unplug the amp, wait 30 seconds and also turn it off at the on/off switch before plugging it back in. It will give the amp time to shut down normally before the power comes back.