I don't know why there is so much T-Amp bashing around here. Maybe because it's all the over-stated claims that the $30 amp is better than a $10,000 tube amp, or whatever. Anyway, it's a $30 amp. I have no doubt that the $125 super T-Amp is better, or that the $400+ clari-T is better, or that the 41hz kit works better. all of those cost more than 4 or 5 times the price, and may require you to solder and tinker. If that's what you're looking for, go for it. None of those comments should be attacks on the $30 T-Amp because it is less expensive and doesn't require tinkering skills and time.
AV123 announced about 5 months ago that they would have a $100 50 watt chip amp, and rumors abound that it sounds good. But there is no product - just hype. It's three times the price of the T-Amp, and not available. I'm not saying don't wait for it - maybe the release is around the corner, but it's not out yet even after delivery was promissed months ago. Scant information on their website and discussion forum about when it will be released, and my inquiries have gotten "we have no information" responses. Furthermore, no one really knows how it will sound, do they? I hope it sounds great. They have delivered a pretty nice looking bookshelf speaker for $240 delivered that is supposed to sound good (although very oddly you can't get grills for it). They've announced a lot of other products, but they seem to announce things long before they actually deliver. Only time will tell whether the product will be available and whether it will be any good.
Finally, people keep saying that the T-Amp isn't powerful enough for regular bookshelf speakers. Those comments are utter nonsense. I'm using the amp with 4 different bookshelf speakers, and it's plenty powerful. There are hundreds of other reviews here and throughout the web saying the same thing. There is no clipping and no distortion at quite loud volumes - too load for me to listen to. And there is room left on the dial. So you can listen to people who are reading charts, or you can listen to people who are actually using the amp with real speakers.
If you are not running efficient bookshelf speakers, it's not a good amp for you. Someone on the forums was complaining that the T-Amp did a bad job of powering a subwoofer. Well, of course it would. It's not a powerful amp. But it sounds great when properly used with in the right speakers and a good regulated power supply.
Whether you should spend the extra $$ on the Super-T or one of the other incarnations depends on whether the extra benefits are worth the extra costs. If you're buying $1,000+ bookshelf speakers, it would probably make sense to get the better build quality and presumably better sound of the Super-T or one of the other improvements. If you're running $200 speakers and don't want to spend the extra money, I think you'll be pleased (as I am) with the stock t-amp. If you like to tinker, you can upgrade it later. If you don't, you can sell it, give it to a friend, or throw it away later. You'll be out, at most, $40.
Bottom line: There is no other amp available in it's price range that is any good at all. None. You have to spend over $100 for the upgraded amps for relatively small improvements in sound quality (but maybe some significant improvements in build quality). Receivers under $200 are generally junk, and will not, in my opinion, compare to the sound of the T-Amp. I have used many. Receivers are inherently noisy because of all of the tone controls and circuitry. The additional claimed wattage of cheap receivers may or may not be true, but in any case is only important if you need the wattage for the speakers you are running.