The Texas Star and the TNT 350 had use about the same bias scheme, making the Texas Star a class B amp and not really s class AB amp. This info was provided to me by a good amp tech and a couple others as well. The TNT 350hd is a great little amp and is well built.
I have an older version of this amp called the magnaforce 350hd, and it has toshiba 2879's in it compared to the new PP100 transistors being used now in the new TNT350hd amps.
Like I said, don't drive the piss out of it and keep it at about 200-250 watts max pep and the amp will last a lot longer. Also about a 2 watt dead key seems to work well with the magnaforce 350hd i have. PEP input numbers on my amp compared to the new tnt 350hd won't be the same.
Not bashing the Texas Star amps, but they are not a true class AB biased amp. Read into this more and you'll find that they are more a class B amp and if overdriven will be a class C amp. Same with the TNT 350hd. Again, keep the input drive levels at the proper levels and the amp will run clean on both AM and SSB. JMHO's.