Yep, my 'switch' is the same - a bit of a pop but it's normal.....
My TB750-A is superb and wouldn't be without it..as has been said, can't get a bad sound from it and very easy to dial-in what I need via Enahnce and Timbre
By the way, the Trace Elliot AH I bought from Ziggy is awesome, really loving it, top bloke to deal with so potential purchasers should have every confidence....