Re: 5150 vs ADA 3tm for recording
either one would be good, as long as you mic the cab.
i didn't listen to the clips, but micing is almost always better. rock guitars live in the realm of pushing air. even though i do use line6 products, the DI sound of them is good and usable, but the sound of a mic'd up cab with a transformer based preamp is the sound of rock/metal.
do yourself a favor and get either an shure sm57, sm7b, audix i5, sennheiser e609, e906, md421, or cascade fathead. those coupled with a GAP pre-73 will give killer guitar tracks! remember, mic placement is very important, too. if you find one sound too bassy, move the mic closer to the center of the cone, too bitey, move it away. more room, pull the mic back about 6-12 inches. really up front, within 2-4 inches from the speaker.
ultimately, are you happy with the sound now? if it ain't broke don't fix it. if your just gas'ing, buy the 5150 and have another flavor.
btw, the 5150 is a great recording amp.