Hi Rojo, I'm really confused. The amp you suggested is SMSL SA-98E in ali express has varies watt output, 160, 120, 100. which one is genuine one. I found this one is free shipping to Australia goo.gl/DyfA3X
BTW is that class D? what is different between class D and T, I heard class T is better, isn't it?
Sorry I'm still newbie
All those wattage values are genuine. When the gain is turned up to the point that there's 10% THD, the amp is pushing 160 watts to a 4 ohm load, 120 watts to 6 ohms, or 100 watts to 8 ohms. The same amp is rated differently by different sellers -- like
this eBay auction at 140, 105, and 70. Part of the discrepancy could also be attributed to the fact that the amp can be fed from a power supply that's anywhere from 24V to 36V. Maybe some of the lower measurements were taken with a 24V power supply?
Typically, though, amps aren't rated at such a high distortion rate. I'd use those values to guess at a more conservative rating of 80 / 60 / 50W @ 0.1% THD or thereabouts. Different manufacturers rate their amps using different criteria, so the actual ratings are more of a guideline estimate than gospel truth -- more a means of comparing different amps by the same manufacturer than anything. Also, amps are rated using a monophonic signal (Sing, Johnny One Note!), which offers very little to predict their real-world performance of playing polyphonic signals through complex speaker loads. To complicate matters even further, your speakers are rated at 6 ohms, but they aren't a consistent 6 ohms throughout the entire 60-ish Hz - 20,000Hz range. Two other things to note are that the difference between 80W and 160W is only 3dB, and most listening is done at < 10W, regardless of the amp's rating. A stronger amp is better at supplying power for peaks, for better dynamics without clipping, so getting as high power an amp as you can (within reason) is a good idea. In other words, even though you may only be listening at 5 watts of power RMS, an 80W amp is still better than a 50W for doing so.
So how does one pick an amp from such a complicated, deceptive mess? Well, doing what you're doing, asking around and leaning on other people's experiences is the best way, really. Looking for independent 3rd-party measurements is another. In any case, SMSL makes solid amps for the money. There's your word-of-mouth recommendation.
Re: amp classes, class T is a type of class D amp. See
AH's amp classes article and the Wikipedia entry for
class T amps.
Re: the amp you found with free shipping to AU, be careful to read what you're agreeing to. That one does not include a power adapter. You'll have to purchase a separate 36V power supply.
Anyway, no need to apologize for your rookie status. Nobody knows everything.
