Amp tripping circuit breaker.

I meant 20 amp not 29 amp breaker.

Yes it’s 20 amp wiring.

Trouble shooting 101...replace the least expensive item first.  Replace the breaker and see what happens. 

NEVER change 2 things at once.

Ground at wall outlet?

I can understand lost confidence in the amp, but, the advice to replace the breaker first is the best.

If electrician does it, he/she can also test ground, at the panel and at the wall outlet.

That will tell you whether it was the ground, breaker, or the amp.

IF, after replacing breaker, ground confirmed, with amp connected, turned off, new breaker trips, curious indeed. Test that before electrician leaves.

Do you have any other equip you could substitute for amp, to see if problem goes away? 

IOW, think like an electrician rather than as an audiophile.

New amp after circuit confirmation? Always fun. Keep in mind, you won't be able to sell the existing amp unless you confirm it was the breaker, not the amp. Another reason not to change two things at once.

I had the same thing happen, but only with a particular high current amp. Other more modest amps would not trip the breaker. But if I plugged the high current amp in any other circuit it would not trip a breaker.

I haven't done so yet, but replacing the breaker is on my to do list.